diff --git a/include/grpc++/support/channel_arguments.h b/include/grpc++/support/channel_arguments.h
index 7b6befeaf1e..9dc505f0082 100644
--- a/include/grpc++/support/channel_arguments.h
+++ b/include/grpc++/support/channel_arguments.h
@@ -64,6 +64,12 @@ class ChannelArguments {
   /// Set the compression algorithm for the channel.
   void SetCompressionAlgorithm(grpc_compression_algorithm algorithm);
 
+  /// Set the grpclb fallback timeout (in ms) for the channel. If this amount
+  /// of time has passed but we have not gotten any non-empty \a serverlist from
+  /// the balancer, we will fall back to use the backend address(es) returned by
+  /// the resolver.
+  void SetGrpclbFallbackTimeout(int fallback_timeout);
+
   /// Set the socket mutator for the channel.
   void SetSocketMutator(grpc_socket_mutator* mutator);
 
diff --git a/include/grpc/impl/codegen/grpc_types.h b/include/grpc/impl/codegen/grpc_types.h
index 90f03f49a3e..65463bb33b6 100644
--- a/include/grpc/impl/codegen/grpc_types.h
+++ b/include/grpc/impl/codegen/grpc_types.h
@@ -288,7 +288,11 @@ typedef struct {
   "grpc.experimental.tcp_max_read_chunk_size"
 /* Timeout in milliseconds to use for calls to the grpclb load balancer.
    If 0 or unset, the balancer calls will have no deadline. */
-#define GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS "grpc.grpclb_timeout_ms"
+#define GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS "grpc.grpclb_call_timeout_ms"
+/* Timeout in milliseconds to wait for the serverlist from the grpclb load
+   balancer before using fallback backend addresses from the resolver.
+   If 0, fallback will never be used. */
+#define GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS "grpc.grpclb_fallback_timeout_ms"
 /** If non-zero, grpc server's cronet compression workaround will be enabled */
 #define GRPC_ARG_WORKAROUND_CRONET_COMPRESSION \
   "grpc.workaround.cronet_compression"
diff --git a/include/grpc/impl/codegen/port_platform.h b/include/grpc/impl/codegen/port_platform.h
index 1904c636f75..7e5f85253e1 100644
--- a/include/grpc/impl/codegen/port_platform.h
+++ b/include/grpc/impl/codegen/port_platform.h
@@ -183,7 +183,6 @@
 #define _BSD_SOURCE
 #endif
 #if TARGET_OS_IPHONE
-#define GPR_FORBID_UNREACHABLE_CODE 1
 #define GPR_PLATFORM_STRING "ios"
 #define GPR_CPU_IPHONE 1
 #define GPR_PTHREAD_TLS 1
diff --git a/src/core/ext/filters/client_channel/http_proxy.c b/src/core/ext/filters/client_channel/http_proxy.c
index c507a2750e2..a16b44d3dc3 100644
--- a/src/core/ext/filters/client_channel/http_proxy.c
+++ b/src/core/ext/filters/client_channel/http_proxy.c
@@ -91,6 +91,7 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
   char* user_cred = NULL;
   *name_to_resolve = get_http_proxy_server(exec_ctx, &user_cred);
   if (*name_to_resolve == NULL) return false;
+  char* no_proxy_str = NULL;
   grpc_uri* uri =
       grpc_uri_parse(exec_ctx, server_uri, false /* suppress_errors */);
   if (uri == NULL || uri->path[0] == '\0') {
@@ -98,20 +99,14 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
             "'http_proxy' environment variable set, but cannot "
             "parse server URI '%s' -- not using proxy",
             server_uri);
-    if (uri != NULL) {
-      gpr_free(user_cred);
-      grpc_uri_destroy(uri);
-    }
-    return false;
+    goto no_use_proxy;
   }
   if (strcmp(uri->scheme, "unix") == 0) {
     gpr_log(GPR_INFO, "not using proxy for Unix domain socket '%s'",
             server_uri);
-    gpr_free(user_cred);
-    grpc_uri_destroy(uri);
-    return false;
+    goto no_use_proxy;
   }
-  char* no_proxy_str = gpr_getenv("no_proxy");
+  no_proxy_str = gpr_getenv("no_proxy");
   if (no_proxy_str != NULL) {
     static const char* NO_PROXY_SEPARATOR = ",";
     bool use_proxy = true;
@@ -147,12 +142,7 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
       gpr_free(no_proxy_hosts);
       gpr_free(server_host);
       gpr_free(server_port);
-      if (!use_proxy) {
-        grpc_uri_destroy(uri);
-        gpr_free(*name_to_resolve);
-        *name_to_resolve = NULL;
-        return false;
-      }
+      if (!use_proxy) goto no_use_proxy;
     }
   }
   grpc_arg args_to_add[2];
@@ -173,9 +163,15 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
   } else {
     *new_args = grpc_channel_args_copy_and_add(args, args_to_add, 1);
   }
-  gpr_free(user_cred);
   grpc_uri_destroy(uri);
+  gpr_free(user_cred);
   return true;
+no_use_proxy:
+  if (uri != NULL) grpc_uri_destroy(uri);
+  gpr_free(*name_to_resolve);
+  *name_to_resolve = NULL;
+  gpr_free(user_cred);
+  return false;
 }
 
 static bool proxy_mapper_map_address(grpc_exec_ctx* exec_ctx,
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
index 85ef7894ea6..8dc81b46d13 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
@@ -123,6 +123,7 @@
 #define GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER 1.6
 #define GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS 120
 #define GRPC_GRPCLB_RECONNECT_JITTER 0.2
+#define GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS 10000
 
 grpc_tracer_flag grpc_lb_glb_trace = GRPC_TRACER_INITIALIZER(false, "glb");
 
@@ -299,6 +300,10 @@ typedef struct glb_lb_policy {
   /** timeout in milliseconds for the LB call. 0 means no deadline. */
   int lb_call_timeout_ms;
 
+  /** timeout in milliseconds for before using fallback backend addresses.
+   * 0 means not using fallback. */
+  int lb_fallback_timeout_ms;
+
   /** for communicating with the LB server */
   grpc_channel *lb_channel;
 
@@ -325,6 +330,9 @@ typedef struct glb_lb_policy {
    * Otherwise, we delegate to the RR policy. */
   size_t serverlist_index;
 
+  /** stores the backend addresses from the resolver */
+  grpc_lb_addresses *fallback_backend_addresses;
+
   /** list of picks that are waiting on RR's policy connectivity */
   pending_pick *pending_picks;
 
@@ -345,6 +353,9 @@ typedef struct glb_lb_policy {
   /** is \a lb_call_retry_timer active? */
   bool retry_timer_active;
 
+  /** is \a lb_fallback_timer active? */
+  bool fallback_timer_active;
+
   /** called upon changes to the LB channel's connectivity. */
   grpc_closure lb_channel_on_connectivity_changed;
 
@@ -354,9 +365,6 @@ typedef struct glb_lb_policy {
   /************************************************************/
   /*  client data associated with the LB server communication */
   /************************************************************/
-  /* Finished sending initial request. */
-  grpc_closure lb_on_sent_initial_request;
-
   /* Status from the LB server has been received. This signals the end of the LB
    * call. */
   grpc_closure lb_on_server_status_received;
@@ -367,6 +375,9 @@ typedef struct glb_lb_policy {
   /* LB call retry timer callback. */
   grpc_closure lb_on_call_retry;
 
+  /* LB fallback timer callback. */
+  grpc_closure lb_on_fallback;
+
   grpc_call *lb_call; /* streaming call to the LB server, */
 
   grpc_metadata_array lb_initial_metadata_recv; /* initial MD from LB server */
@@ -390,7 +401,9 @@ typedef struct glb_lb_policy {
   /** LB call retry timer */
   grpc_timer lb_call_retry_timer;
 
-  bool initial_request_sent;
+  /** LB fallback timer */
+  grpc_timer lb_fallback_timer;
+
   bool seen_initial_response;
 
   /* Stats for client-side load reporting. Should be unreffed and
@@ -536,6 +549,32 @@ static grpc_lb_addresses *process_serverlist_locked(
   return lb_addresses;
 }
 
+/* Returns the backend addresses extracted from the given addresses */
+static grpc_lb_addresses *extract_backend_addresses_locked(
+    grpc_exec_ctx *exec_ctx, const grpc_lb_addresses *addresses) {
+  /* first pass: count the number of backend addresses */
+  size_t num_backends = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (!addresses->addresses[i].is_balancer) {
+      ++num_backends;
+    }
+  }
+  /* second pass: actually populate the addresses and (empty) LB tokens */
+  grpc_lb_addresses *backend_addresses =
+      grpc_lb_addresses_create(num_backends, &lb_token_vtable);
+  size_t num_copied = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (addresses->addresses[i].is_balancer) continue;
+    const grpc_resolved_address *addr = &addresses->addresses[i].address;
+    grpc_lb_addresses_set_address(backend_addresses, num_copied, &addr->addr,
+                                  addr->len, false /* is_balancer */,
+                                  NULL /* balancer_name */,
+                                  (void *)GRPC_MDELEM_LB_TOKEN_EMPTY.payload);
+    ++num_copied;
+  }
+  return backend_addresses;
+}
+
 static void update_lb_connectivity_status_locked(
     grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
     grpc_connectivity_state rr_state, grpc_error *rr_state_error) {
@@ -603,35 +642,38 @@ static bool pick_from_internal_rr_locked(
     grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
     const grpc_lb_policy_pick_args *pick_args, bool force_async,
     grpc_connected_subchannel **target, wrapped_rr_closure_arg *wc_arg) {
-  // Look at the index into the serverlist to see if we should drop this call.
-  grpc_grpclb_server *server =
-      glb_policy->serverlist->servers[glb_policy->serverlist_index++];
-  if (glb_policy->serverlist_index == glb_policy->serverlist->num_servers) {
-    glb_policy->serverlist_index = 0;  // Wrap-around.
-  }
-  if (server->drop) {
-    // Not using the RR policy, so unref it.
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO, "Unreffing RR for drop (0x%" PRIxPTR ")",
-              (intptr_t)wc_arg->rr_policy);
+  // Check for drops if we are not using fallback backend addresses.
+  if (glb_policy->serverlist != NULL) {
+    // Look at the index into the serverlist to see if we should drop this call.
+    grpc_grpclb_server *server =
+        glb_policy->serverlist->servers[glb_policy->serverlist_index++];
+    if (glb_policy->serverlist_index == glb_policy->serverlist->num_servers) {
+      glb_policy->serverlist_index = 0;  // Wrap-around.
     }
-    GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "glb_pick_sync");
-    // Update client load reporting stats to indicate the number of
-    // dropped calls.  Note that we have to do this here instead of in
-    // the client_load_reporting filter, because we do not create a
-    // subchannel call (and therefore no client_load_reporting filter)
-    // for dropped calls.
-    grpc_grpclb_client_stats_add_call_dropped_locked(server->load_balance_token,
-                                                     wc_arg->client_stats);
-    grpc_grpclb_client_stats_unref(wc_arg->client_stats);
-    if (force_async) {
-      GPR_ASSERT(wc_arg->wrapped_closure != NULL);
-      GRPC_CLOSURE_SCHED(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_NONE);
+    if (server->drop) {
+      // Not using the RR policy, so unref it.
+      if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+        gpr_log(GPR_INFO, "Unreffing RR for drop (0x%" PRIxPTR ")",
+                (intptr_t)wc_arg->rr_policy);
+      }
+      GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "glb_pick_sync");
+      // Update client load reporting stats to indicate the number of
+      // dropped calls.  Note that we have to do this here instead of in
+      // the client_load_reporting filter, because we do not create a
+      // subchannel call (and therefore no client_load_reporting filter)
+      // for dropped calls.
+      grpc_grpclb_client_stats_add_call_dropped_locked(
+          server->load_balance_token, wc_arg->client_stats);
+      grpc_grpclb_client_stats_unref(wc_arg->client_stats);
+      if (force_async) {
+        GPR_ASSERT(wc_arg->wrapped_closure != NULL);
+        GRPC_CLOSURE_SCHED(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_NONE);
+        gpr_free(wc_arg->free_when_done);
+        return false;
+      }
       gpr_free(wc_arg->free_when_done);
-      return false;
+      return true;
     }
-    gpr_free(wc_arg->free_when_done);
-    return true;
   }
   // Pick via the RR policy.
   const bool pick_done = grpc_lb_policy_pick_locked(
@@ -669,8 +711,18 @@ static bool pick_from_internal_rr_locked(
 
 static grpc_lb_policy_args *lb_policy_args_create(grpc_exec_ctx *exec_ctx,
                                                   glb_lb_policy *glb_policy) {
-  grpc_lb_addresses *addresses =
-      process_serverlist_locked(exec_ctx, glb_policy->serverlist);
+  grpc_lb_addresses *addresses;
+  if (glb_policy->serverlist != NULL) {
+    GPR_ASSERT(glb_policy->serverlist->num_servers > 0);
+    addresses = process_serverlist_locked(exec_ctx, glb_policy->serverlist);
+  } else {
+    // If rr_handover_locked() is invoked when we haven't received any
+    // serverlist from the balancer, we use the fallback backends returned by
+    // the resolver. Note that the fallback backend list may be empty, in which
+    // case the new round_robin policy will keep the requested picks pending.
+    GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
+    addresses = grpc_lb_addresses_copy(glb_policy->fallback_backend_addresses);
+  }
   GPR_ASSERT(addresses != NULL);
   grpc_lb_policy_args *args = (grpc_lb_policy_args *)gpr_zalloc(sizeof(*args));
   args->client_channel_factory = glb_policy->cc_factory;
@@ -776,8 +828,6 @@ static void create_rr_locked(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
 /* glb_policy->rr_policy may be NULL (initial handover) */
 static void rr_handover_locked(grpc_exec_ctx *exec_ctx,
                                glb_lb_policy *glb_policy) {
-  GPR_ASSERT(glb_policy->serverlist != NULL &&
-             glb_policy->serverlist->num_servers > 0);
   if (glb_policy->shutting_down) return;
   grpc_lb_policy_args *args = lb_policy_args_create(exec_ctx, glb_policy);
   GPR_ASSERT(args != NULL);
@@ -926,6 +976,9 @@ static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   if (glb_policy->serverlist != NULL) {
     grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
   }
+  if (glb_policy->fallback_backend_addresses != NULL) {
+    grpc_lb_addresses_destroy(exec_ctx, glb_policy->fallback_backend_addresses);
+  }
   grpc_fake_resolver_response_generator_unref(glb_policy->response_generator);
   grpc_subchannel_index_unref();
   if (glb_policy->pending_update_args != NULL) {
@@ -1067,10 +1120,28 @@ static void glb_cancel_picks_locked(grpc_exec_ctx *exec_ctx,
   GRPC_ERROR_UNREF(error);
 }
 
+static void lb_on_fallback_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                        grpc_error *error);
 static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
                                       glb_lb_policy *glb_policy);
 static void start_picking_locked(grpc_exec_ctx *exec_ctx,
                                  glb_lb_policy *glb_policy) {
+  /* start a timer to fall back */
+  if (glb_policy->lb_fallback_timeout_ms > 0 &&
+      glb_policy->serverlist == NULL && !glb_policy->fallback_timer_active) {
+    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
+    gpr_timespec deadline = gpr_time_add(
+        now,
+        gpr_time_from_millis(glb_policy->lb_fallback_timeout_ms, GPR_TIMESPAN));
+    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_fallback_timer");
+    GRPC_CLOSURE_INIT(&glb_policy->lb_on_fallback, lb_on_fallback_timer_locked,
+                      glb_policy,
+                      grpc_combiner_scheduler(glb_policy->base.combiner));
+    glb_policy->fallback_timer_active = true;
+    grpc_timer_init(exec_ctx, &glb_policy->lb_fallback_timer, deadline,
+                    &glb_policy->lb_on_fallback, now);
+  }
+
   glb_policy->started_picking = true;
   gpr_backoff_reset(&glb_policy->lb_call_backoff_state);
   query_for_backends_locked(exec_ctx, glb_policy);
@@ -1173,6 +1244,58 @@ static void glb_notify_on_state_change_locked(grpc_exec_ctx *exec_ctx,
       exec_ctx, &glb_policy->state_tracker, current, notify);
 }
 
+static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                          grpc_error *error) {
+  glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
+  glb_policy->retry_timer_active = false;
+  if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_INFO, "Restaring call to LB server (grpclb %p)",
+              (void *)glb_policy);
+    }
+    GPR_ASSERT(glb_policy->lb_call == NULL);
+    query_for_backends_locked(exec_ctx, glb_policy);
+  }
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, "grpclb_retry_timer");
+}
+
+static void maybe_restart_lb_call(grpc_exec_ctx *exec_ctx,
+                                  glb_lb_policy *glb_policy) {
+  if (glb_policy->started_picking && glb_policy->updating_lb_call) {
+    if (glb_policy->retry_timer_active) {
+      grpc_timer_cancel(exec_ctx, &glb_policy->lb_call_retry_timer);
+    }
+    if (!glb_policy->shutting_down) start_picking_locked(exec_ctx, glb_policy);
+    glb_policy->updating_lb_call = false;
+  } else if (!glb_policy->shutting_down) {
+    /* if we aren't shutting down, restart the LB client call after some time */
+    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
+    gpr_timespec next_try =
+        gpr_backoff_step(&glb_policy->lb_call_backoff_state, now);
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_DEBUG, "Connection to LB server lost (grpclb: %p)...",
+              (void *)glb_policy);
+      gpr_timespec timeout = gpr_time_sub(next_try, now);
+      if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) {
+        gpr_log(GPR_DEBUG,
+                "... retry_timer_active in %" PRId64 ".%09d seconds.",
+                timeout.tv_sec, timeout.tv_nsec);
+      } else {
+        gpr_log(GPR_DEBUG, "... retry_timer_active immediately.");
+      }
+    }
+    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
+    GRPC_CLOSURE_INIT(&glb_policy->lb_on_call_retry,
+                      lb_call_on_retry_timer_locked, glb_policy,
+                      grpc_combiner_scheduler(glb_policy->base.combiner));
+    glb_policy->retry_timer_active = true;
+    grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
+                    &glb_policy->lb_on_call_retry, now);
+  }
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
+                            "lb_on_server_status_received_locked");
+}
+
 static void send_client_load_report_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                            grpc_error *error);
 
@@ -1203,21 +1326,6 @@ static void client_load_report_done_locked(grpc_exec_ctx *exec_ctx, void *arg,
   schedule_next_client_load_report(exec_ctx, glb_policy);
 }
 
-static void do_send_client_load_report_locked(grpc_exec_ctx *exec_ctx,
-                                              glb_lb_policy *glb_policy) {
-  grpc_op op;
-  memset(&op, 0, sizeof(op));
-  op.op = GRPC_OP_SEND_MESSAGE;
-  op.data.send_message.send_message = glb_policy->client_load_report_payload;
-  GRPC_CLOSURE_INIT(&glb_policy->client_load_report_closure,
-                    client_load_report_done_locked, glb_policy,
-                    grpc_combiner_scheduler(glb_policy->base.combiner));
-  grpc_call_error call_error = grpc_call_start_batch_and_execute(
-      exec_ctx, glb_policy->lb_call, &op, 1,
-      &glb_policy->client_load_report_closure);
-  GPR_ASSERT(GRPC_CALL_OK == call_error);
-}
-
 static bool load_report_counters_are_zero(grpc_grpclb_request *request) {
   grpc_grpclb_dropped_call_counts *drop_entries =
       (grpc_grpclb_dropped_call_counts *)
@@ -1237,6 +1345,9 @@ static void send_client_load_report_locked(grpc_exec_ctx *exec_ctx, void *arg,
     glb_policy->client_load_report_timer_pending = false;
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                               "client_load_report");
+    if (glb_policy->lb_call == NULL) {
+      maybe_restart_lb_call(exec_ctx, glb_policy);
+    }
     return;
   }
   // Construct message payload.
@@ -1260,17 +1371,23 @@ static void send_client_load_report_locked(grpc_exec_ctx *exec_ctx, void *arg,
       grpc_raw_byte_buffer_create(&request_payload_slice, 1);
   grpc_slice_unref_internal(exec_ctx, request_payload_slice);
   grpc_grpclb_request_destroy(request);
-  // If we've already sent the initial request, then we can go ahead and
-  // sent the load report.  Otherwise, we need to wait until the initial
-  // request has been sent to send this
-  // (see lb_on_sent_initial_request_locked() below).
-  if (glb_policy->initial_request_sent) {
-    do_send_client_load_report_locked(exec_ctx, glb_policy);
+  // Send load report message.
+  grpc_op op;
+  memset(&op, 0, sizeof(op));
+  op.op = GRPC_OP_SEND_MESSAGE;
+  op.data.send_message.send_message = glb_policy->client_load_report_payload;
+  GRPC_CLOSURE_INIT(&glb_policy->client_load_report_closure,
+                    client_load_report_done_locked, glb_policy,
+                    grpc_combiner_scheduler(glb_policy->base.combiner));
+  grpc_call_error call_error = grpc_call_start_batch_and_execute(
+      exec_ctx, glb_policy->lb_call, &op, 1,
+      &glb_policy->client_load_report_closure);
+  if (call_error != GRPC_CALL_OK) {
+    gpr_log(GPR_ERROR, "call_error=%d", call_error);
+    GPR_ASSERT(GRPC_CALL_OK == call_error);
   }
 }
 
-static void lb_on_sent_initial_request_locked(grpc_exec_ctx *exec_ctx,
-                                              void *arg, grpc_error *error);
 static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
                                                 void *arg, grpc_error *error);
 static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
@@ -1315,9 +1432,6 @@ static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
   grpc_slice_unref_internal(exec_ctx, request_payload_slice);
   grpc_grpclb_request_destroy(request);
 
-  GRPC_CLOSURE_INIT(&glb_policy->lb_on_sent_initial_request,
-                    lb_on_sent_initial_request_locked, glb_policy,
-                    grpc_combiner_scheduler(glb_policy->base.combiner));
   GRPC_CLOSURE_INIT(&glb_policy->lb_on_server_status_received,
                     lb_on_server_status_received_locked, glb_policy,
                     grpc_combiner_scheduler(glb_policy->base.combiner));
@@ -1332,7 +1446,6 @@ static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
                    GRPC_GRPCLB_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
                    GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
 
-  glb_policy->initial_request_sent = false;
   glb_policy->seen_initial_response = false;
   glb_policy->last_client_load_report_counters_were_zero = false;
 }
@@ -1349,7 +1462,7 @@ static void lb_call_destroy_locked(grpc_exec_ctx *exec_ctx,
   grpc_byte_buffer_destroy(glb_policy->lb_request_payload);
   grpc_slice_unref_internal(exec_ctx, glb_policy->lb_call_status_details);
 
-  if (!glb_policy->client_load_report_timer_pending) {
+  if (glb_policy->client_load_report_timer_pending) {
     grpc_timer_cancel(exec_ctx, &glb_policy->client_load_report_timer);
   }
 }
@@ -1373,7 +1486,7 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(glb_policy->lb_call != NULL);
 
   grpc_call_error call_error;
-  grpc_op ops[4];
+  grpc_op ops[3];
   memset(ops, 0, sizeof(ops));
 
   grpc_op *op = ops;
@@ -1394,13 +1507,8 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   op->flags = 0;
   op->reserved = NULL;
   op++;
-  /* take a weak ref (won't prevent calling of \a glb_shutdown if the strong ref
-   * count goes to zero) to be unref'd in lb_on_sent_initial_request_locked() */
-  GRPC_LB_POLICY_WEAK_REF(&glb_policy->base,
-                          "lb_on_sent_initial_request_locked");
-  call_error = grpc_call_start_batch_and_execute(
-      exec_ctx, glb_policy->lb_call, ops, (size_t)(op - ops),
-      &glb_policy->lb_on_sent_initial_request);
+  call_error = grpc_call_start_batch_and_execute(exec_ctx, glb_policy->lb_call,
+                                                 ops, (size_t)(op - ops), NULL);
   GPR_ASSERT(GRPC_CALL_OK == call_error);
 
   op = ops;
@@ -1437,19 +1545,6 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(GRPC_CALL_OK == call_error);
 }
 
-static void lb_on_sent_initial_request_locked(grpc_exec_ctx *exec_ctx,
-                                              void *arg, grpc_error *error) {
-  glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
-  glb_policy->initial_request_sent = true;
-  // If we attempted to send a client load report before the initial
-  // request was sent, send the load report now.
-  if (glb_policy->client_load_report_payload != NULL) {
-    do_send_client_load_report_locked(exec_ctx, glb_policy);
-  }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
-                            "lb_on_sent_initial_request_locked");
-}
-
 static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                            grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
@@ -1525,6 +1620,15 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
             if (glb_policy->serverlist != NULL) {
               /* dispose of the old serverlist */
               grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
+            } else {
+              /* or dispose of the fallback */
+              grpc_lb_addresses_destroy(exec_ctx,
+                                        glb_policy->fallback_backend_addresses);
+              glb_policy->fallback_backend_addresses = NULL;
+              if (glb_policy->fallback_timer_active) {
+                grpc_timer_cancel(exec_ctx, &glb_policy->lb_fallback_timer);
+                glb_policy->fallback_timer_active = false;
+              }
             }
             /* and update the copy in the glb_lb_policy instance. This
              * serverlist instance will be destroyed either upon the next
@@ -1535,9 +1639,7 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
           }
         } else {
           if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-            gpr_log(GPR_INFO,
-                    "Received empty server list. Picks will stay pending until "
-                    "a response with > 0 servers is received");
+            gpr_log(GPR_INFO, "Received empty server list, ignoring.");
           }
           grpc_grpclb_destroy_serverlist(serverlist);
         }
@@ -1572,19 +1674,25 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
   }
 }
 
-static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                                          grpc_error *error) {
+static void lb_on_fallback_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                        grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
-  glb_policy->retry_timer_active = false;
-  if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO, "Restaring call to LB server (grpclb %p)",
-              (void *)glb_policy);
+  glb_policy->fallback_timer_active = false;
+  /* If we receive a serverlist after the timer fires but before this callback
+   * actually runs, don't fall back. */
+  if (glb_policy->serverlist == NULL) {
+    if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
+      if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+        gpr_log(GPR_INFO,
+                "Falling back to use backends from resolver (grpclb %p)",
+                (void *)glb_policy);
+      }
+      GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
+      rr_handover_locked(exec_ctx, glb_policy);
     }
-    GPR_ASSERT(glb_policy->lb_call == NULL);
-    query_for_backends_locked(exec_ctx, glb_policy);
   }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, "grpclb_retry_timer");
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
+                            "grpclb_fallback_timer");
 }
 
 static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
@@ -1603,66 +1711,30 @@ static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
   }
   /* We need to perform cleanups no matter what. */
   lb_call_destroy_locked(exec_ctx, glb_policy);
-  if (glb_policy->started_picking && glb_policy->updating_lb_call) {
-    if (glb_policy->retry_timer_active) {
-      grpc_timer_cancel(exec_ctx, &glb_policy->lb_call_retry_timer);
-    }
-    if (!glb_policy->shutting_down) start_picking_locked(exec_ctx, glb_policy);
-    glb_policy->updating_lb_call = false;
-  } else if (!glb_policy->shutting_down) {
-    /* if we aren't shutting down, restart the LB client call after some time */
-    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-    gpr_timespec next_try =
-        gpr_backoff_step(&glb_policy->lb_call_backoff_state, now);
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_DEBUG, "Connection to LB server lost (grpclb: %p)...",
-              (void *)glb_policy);
-      gpr_timespec timeout = gpr_time_sub(next_try, now);
-      if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) {
-        gpr_log(GPR_DEBUG,
-                "... retry_timer_active in %" PRId64 ".%09d seconds.",
-                timeout.tv_sec, timeout.tv_nsec);
-      } else {
-        gpr_log(GPR_DEBUG, "... retry_timer_active immediately.");
-      }
-    }
-    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
-    GRPC_CLOSURE_INIT(&glb_policy->lb_on_call_retry,
-                      lb_call_on_retry_timer_locked, glb_policy,
-                      grpc_combiner_scheduler(glb_policy->base.combiner));
-    glb_policy->retry_timer_active = true;
-    grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
-                    &glb_policy->lb_on_call_retry, now);
+  // If the load report timer is still pending, we wait for it to be
+  // called before restarting the call.  Otherwise, we restart the call
+  // here.
+  if (!glb_policy->client_load_report_timer_pending) {
+    maybe_restart_lb_call(exec_ctx, glb_policy);
+  }
+}
+
+static void fallback_update_locked(grpc_exec_ctx *exec_ctx,
+                                   glb_lb_policy *glb_policy,
+                                   const grpc_lb_addresses *addresses) {
+  GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
+  grpc_lb_addresses_destroy(exec_ctx, glb_policy->fallback_backend_addresses);
+  glb_policy->fallback_backend_addresses =
+      extract_backend_addresses_locked(exec_ctx, addresses);
+  if (glb_policy->lb_fallback_timeout_ms > 0 &&
+      !glb_policy->fallback_timer_active) {
+    rr_handover_locked(exec_ctx, glb_policy);
   }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
-                            "lb_on_server_status_received_locked");
 }
 
 static void glb_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                               const grpc_lb_policy_args *args) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)policy;
-  if (glb_policy->updating_lb_channel) {
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO,
-              "Update already in progress for grpclb %p. Deferring update.",
-              (void *)glb_policy);
-    }
-    if (glb_policy->pending_update_args != NULL) {
-      grpc_channel_args_destroy(exec_ctx,
-                                glb_policy->pending_update_args->args);
-      gpr_free(glb_policy->pending_update_args);
-    }
-    glb_policy->pending_update_args = (grpc_lb_policy_args *)gpr_zalloc(
-        sizeof(*glb_policy->pending_update_args));
-    glb_policy->pending_update_args->client_channel_factory =
-        args->client_channel_factory;
-    glb_policy->pending_update_args->args = grpc_channel_args_copy(args->args);
-    glb_policy->pending_update_args->combiner = args->combiner;
-    return;
-  }
-
-  glb_policy->updating_lb_channel = true;
-  // Propagate update to lb_channel (pick first).
   const grpc_arg *arg =
       grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
@@ -1680,13 +1752,43 @@ static void glb_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
               "ignoring.",
               (void *)glb_policy);
     }
+    return;
   }
   const grpc_lb_addresses *addresses =
       (const grpc_lb_addresses *)arg->value.pointer.p;
+
+  if (glb_policy->serverlist == NULL) {
+    // If a non-empty serverlist hasn't been received from the balancer,
+    // propagate the update to fallback_backend_addresses.
+    fallback_update_locked(exec_ctx, glb_policy, addresses);
+  } else if (glb_policy->updating_lb_channel) {
+    // If we have recieved serverlist from the balancer, we need to defer update
+    // when there is an in-progress one.
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_INFO,
+              "Update already in progress for grpclb %p. Deferring update.",
+              (void *)glb_policy);
+    }
+    if (glb_policy->pending_update_args != NULL) {
+      grpc_channel_args_destroy(exec_ctx,
+                                glb_policy->pending_update_args->args);
+      gpr_free(glb_policy->pending_update_args);
+    }
+    glb_policy->pending_update_args = (grpc_lb_policy_args *)gpr_zalloc(
+        sizeof(*glb_policy->pending_update_args));
+    glb_policy->pending_update_args->client_channel_factory =
+        args->client_channel_factory;
+    glb_policy->pending_update_args->args = grpc_channel_args_copy(args->args);
+    glb_policy->pending_update_args->combiner = args->combiner;
+    return;
+  }
+
+  glb_policy->updating_lb_channel = true;
   GPR_ASSERT(glb_policy->lb_channel != NULL);
   grpc_channel_args *lb_channel_args = build_lb_channel_args(
       exec_ctx, addresses, glb_policy->response_generator, args->args);
-  /* Propagate updates to the LB channel through the fake resolver */
+  /* Propagate updates to the LB channel (pick first) through the fake resolver
+   */
   grpc_fake_resolver_response_generator_set_response(
       exec_ctx, glb_policy->response_generator, lb_channel_args);
   grpc_channel_args_destroy(exec_ctx, lb_channel_args);
@@ -1789,13 +1891,7 @@ static const grpc_lb_policy_vtable glb_lb_policy_vtable = {
 static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy_factory *factory,
                                   grpc_lb_policy_args *args) {
-  /* Count the number of gRPC-LB addresses. There must be at least one.
-   * TODO(roth): For now, we ignore non-balancer addresses, but in the
-   * future, we may change the behavior such that we fall back to using
-   * the non-balancer addresses if we cannot reach any balancers. In the
-   * fallback case, we should use the LB policy indicated by
-   * GRPC_ARG_LB_POLICY_NAME (although if that specifies grpclb or is
-   * unset, we should default to pick_first). */
+  /* Count the number of gRPC-LB addresses. There must be at least one. */
   const grpc_arg *arg =
       grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
@@ -1831,6 +1927,11 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_policy->lb_call_timeout_ms =
       grpc_channel_arg_get_integer(arg, (grpc_integer_options){0, 0, INT_MAX});
 
+  arg = grpc_channel_args_find(args->args, GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS);
+  glb_policy->lb_fallback_timeout_ms = grpc_channel_arg_get_integer(
+      arg, (grpc_integer_options){GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS, 0,
+                                  INT_MAX});
+
   // Make sure that GRPC_ARG_LB_POLICY_NAME is set in channel args,
   // since we use this to trigger the client_load_reporting filter.
   grpc_arg new_arg = grpc_channel_arg_string_create(
@@ -1839,6 +1940,11 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_policy->args = grpc_channel_args_copy_and_add_and_remove(
       args->args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), &new_arg, 1);
 
+  /* Extract the backend addresses (may be empty) from the resolver for
+   * fallback. */
+  glb_policy->fallback_backend_addresses =
+      extract_backend_addresses_locked(exec_ctx, addresses);
+
   /* Create a client channel over them to communicate with a LB service */
   glb_policy->response_generator =
       grpc_fake_resolver_response_generator_create();
diff --git a/src/core/ext/filters/client_channel/lb_policy_factory.c b/src/core/ext/filters/client_channel/lb_policy_factory.c
index 4d1405454c9..05ab43d0b69 100644
--- a/src/core/ext/filters/client_channel/lb_policy_factory.c
+++ b/src/core/ext/filters/client_channel/lb_policy_factory.c
@@ -56,7 +56,7 @@ grpc_lb_addresses* grpc_lb_addresses_copy(const grpc_lb_addresses* addresses) {
 }
 
 void grpc_lb_addresses_set_address(grpc_lb_addresses* addresses, size_t index,
-                                   void* address, size_t address_len,
+                                   const void* address, size_t address_len,
                                    bool is_balancer, const char* balancer_name,
                                    void* user_data) {
   GPR_ASSERT(index < addresses->num_addresses);
diff --git a/src/core/ext/filters/client_channel/lb_policy_factory.h b/src/core/ext/filters/client_channel/lb_policy_factory.h
index 9d9fb143df5..cf0f8cb6157 100644
--- a/src/core/ext/filters/client_channel/lb_policy_factory.h
+++ b/src/core/ext/filters/client_channel/lb_policy_factory.h
@@ -73,7 +73,7 @@ grpc_lb_addresses *grpc_lb_addresses_copy(const grpc_lb_addresses *addresses);
  * \a address is a socket address of length \a address_len.
  * Takes ownership of \a balancer_name. */
 void grpc_lb_addresses_set_address(grpc_lb_addresses *addresses, size_t index,
-                                   void *address, size_t address_len,
+                                   const void *address, size_t address_len,
                                    bool is_balancer, const char *balancer_name,
                                    void *user_data);
 
diff --git a/src/core/lib/debug/stats_data.c b/src/core/lib/debug/stats_data.c
index fb6055f7957..c0aec63c1d3 100644
--- a/src/core/lib/debug/stats_data.c
+++ b/src/core/lib/debug/stats_data.c
@@ -109,8 +109,6 @@ const char *grpc_stats_counter_name[GRPC_STATS_COUNTER_COUNT] = {
     "executor_wakeup_initiated",
     "executor_queue_drained",
     "executor_push_retries",
-    "executor_threads_created",
-    "executor_threads_used",
     "server_requested_calls",
     "server_slowpath_requests_queued",
 };
@@ -219,8 +217,6 @@ const char *grpc_stats_counter_doc[GRPC_STATS_COUNTER_COUNT] = {
     "Number of times an executor queue was drained",
     "Number of times we raced and were forced to retry pushing a closure to "
     "the executor",
-    "Size of the backing thread pool for overflow gRPC Core work",
-    "How many executor threads actually got used",
     "How many calls were requested (not necessarily received) by the server",
     "How many times was the server slow path taken (indicates too few "
     "outstanding requests)",
@@ -238,7 +234,6 @@ const char *grpc_stats_histogram_name[GRPC_STATS_HISTOGRAM_COUNT] = {
     "http2_send_message_per_write",
     "http2_send_trailing_metadata_per_write",
     "http2_send_flowctl_per_write",
-    "executor_closures_per_wakeup",
     "server_cqs_checked",
 };
 const char *grpc_stats_histogram_doc[GRPC_STATS_HISTOGRAM_COUNT] = {
@@ -254,7 +249,6 @@ const char *grpc_stats_histogram_doc[GRPC_STATS_HISTOGRAM_COUNT] = {
     "Number of streams whose payload was written per TCP write",
     "Number of streams terminated per TCP write",
     "Number of flow control updates written per TCP write",
-    "Number of closures executed each time an executor wakes up",
     "How many completion queues were checked looking for a CQ that had "
     "requested the incoming call",
 };
@@ -326,7 +320,6 @@ const uint8_t grpc_stats_table_7[102] = {
 const int grpc_stats_table_8[9] = {0, 1, 2, 4, 7, 13, 23, 39, 64};
 const uint8_t grpc_stats_table_9[9] = {0, 0, 1, 2, 2, 3, 4, 4, 5};
 void grpc_stats_inc_call_initial_size(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 262144);
   if (value < 6) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx), GRPC_STATS_HISTOGRAM_CALL_INITIAL_SIZE,
@@ -352,7 +345,6 @@ void grpc_stats_inc_call_initial_size(grpc_exec_ctx *exec_ctx, int value) {
                                (exec_ctx), value, grpc_stats_table_0, 64));
 }
 void grpc_stats_inc_poll_events_returned(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 29) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx),
@@ -379,7 +371,6 @@ void grpc_stats_inc_poll_events_returned(grpc_exec_ctx *exec_ctx, int value) {
                                (exec_ctx), value, grpc_stats_table_2, 128));
 }
 void grpc_stats_inc_tcp_write_size(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 16777216);
   if (value < 5) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx), GRPC_STATS_HISTOGRAM_TCP_WRITE_SIZE,
@@ -405,7 +396,6 @@ void grpc_stats_inc_tcp_write_size(grpc_exec_ctx *exec_ctx, int value) {
                                (exec_ctx), value, grpc_stats_table_4, 64));
 }
 void grpc_stats_inc_tcp_write_iov_size(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 13) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx),
@@ -431,7 +421,6 @@ void grpc_stats_inc_tcp_write_iov_size(grpc_exec_ctx *exec_ctx, int value) {
                                (exec_ctx), value, grpc_stats_table_6, 64));
 }
 void grpc_stats_inc_tcp_read_size(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 16777216);
   if (value < 5) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx), GRPC_STATS_HISTOGRAM_TCP_READ_SIZE,
@@ -457,7 +446,6 @@ void grpc_stats_inc_tcp_read_size(grpc_exec_ctx *exec_ctx, int value) {
                                (exec_ctx), value, grpc_stats_table_4, 64));
 }
 void grpc_stats_inc_tcp_read_offer(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 16777216);
   if (value < 5) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx), GRPC_STATS_HISTOGRAM_TCP_READ_OFFER,
@@ -484,7 +472,6 @@ void grpc_stats_inc_tcp_read_offer(grpc_exec_ctx *exec_ctx, int value) {
 }
 void grpc_stats_inc_tcp_read_offer_iov_size(grpc_exec_ctx *exec_ctx,
                                             int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 13) {
     GRPC_STATS_INC_HISTOGRAM(
@@ -512,7 +499,6 @@ void grpc_stats_inc_tcp_read_offer_iov_size(grpc_exec_ctx *exec_ctx,
 }
 void grpc_stats_inc_http2_send_message_size(grpc_exec_ctx *exec_ctx,
                                             int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 16777216);
   if (value < 5) {
     GRPC_STATS_INC_HISTOGRAM(
@@ -540,7 +526,6 @@ void grpc_stats_inc_http2_send_message_size(grpc_exec_ctx *exec_ctx,
 }
 void grpc_stats_inc_http2_send_initial_metadata_per_write(
     grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 13) {
     GRPC_STATS_INC_HISTOGRAM(
@@ -570,7 +555,6 @@ void grpc_stats_inc_http2_send_initial_metadata_per_write(
 }
 void grpc_stats_inc_http2_send_message_per_write(grpc_exec_ctx *exec_ctx,
                                                  int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 13) {
     GRPC_STATS_INC_HISTOGRAM(
@@ -598,7 +582,6 @@ void grpc_stats_inc_http2_send_message_per_write(grpc_exec_ctx *exec_ctx,
 }
 void grpc_stats_inc_http2_send_trailing_metadata_per_write(
     grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 13) {
     GRPC_STATS_INC_HISTOGRAM(
@@ -628,7 +611,6 @@ void grpc_stats_inc_http2_send_trailing_metadata_per_write(
 }
 void grpc_stats_inc_http2_send_flowctl_per_write(grpc_exec_ctx *exec_ctx,
                                                  int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 1024);
   if (value < 13) {
     GRPC_STATS_INC_HISTOGRAM(
@@ -654,36 +636,7 @@ void grpc_stats_inc_http2_send_flowctl_per_write(grpc_exec_ctx *exec_ctx,
                            grpc_stats_histo_find_bucket_slow(
                                (exec_ctx), value, grpc_stats_table_6, 64));
 }
-void grpc_stats_inc_executor_closures_per_wakeup(grpc_exec_ctx *exec_ctx,
-                                                 int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
-  value = GPR_CLAMP(value, 0, 1024);
-  if (value < 13) {
-    GRPC_STATS_INC_HISTOGRAM(
-        (exec_ctx), GRPC_STATS_HISTOGRAM_EXECUTOR_CLOSURES_PER_WAKEUP, value);
-    return;
-  }
-  union {
-    double dbl;
-    uint64_t uint;
-  } _val, _bkt;
-  _val.dbl = value;
-  if (_val.uint < 4637863191261478912ull) {
-    int bucket =
-        grpc_stats_table_7[((_val.uint - 4623507967449235456ull) >> 48)] + 13;
-    _bkt.dbl = grpc_stats_table_6[bucket];
-    bucket -= (_val.uint < _bkt.uint);
-    GRPC_STATS_INC_HISTOGRAM(
-        (exec_ctx), GRPC_STATS_HISTOGRAM_EXECUTOR_CLOSURES_PER_WAKEUP, bucket);
-    return;
-  }
-  GRPC_STATS_INC_HISTOGRAM((exec_ctx),
-                           GRPC_STATS_HISTOGRAM_EXECUTOR_CLOSURES_PER_WAKEUP,
-                           grpc_stats_histo_find_bucket_slow(
-                               (exec_ctx), value, grpc_stats_table_6, 64));
-}
 void grpc_stats_inc_server_cqs_checked(grpc_exec_ctx *exec_ctx, int value) {
-  /* Automatically generated by tools/codegen/core/gen_stats_data.py */
   value = GPR_CLAMP(value, 0, 64);
   if (value < 3) {
     GRPC_STATS_INC_HISTOGRAM((exec_ctx),
@@ -708,17 +661,17 @@ void grpc_stats_inc_server_cqs_checked(grpc_exec_ctx *exec_ctx, int value) {
                            grpc_stats_histo_find_bucket_slow(
                                (exec_ctx), value, grpc_stats_table_8, 8));
 }
-const int grpc_stats_histo_buckets[14] = {64, 128, 64, 64, 64, 64, 64,
-                                          64, 64,  64, 64, 64, 64, 8};
-const int grpc_stats_histo_start[14] = {0,   64,  192, 256, 320, 384, 448,
-                                        512, 576, 640, 704, 768, 832, 896};
-const int *const grpc_stats_histo_bucket_boundaries[14] = {
+const int grpc_stats_histo_buckets[13] = {64, 128, 64, 64, 64, 64, 64,
+                                          64, 64,  64, 64, 64, 8};
+const int grpc_stats_histo_start[13] = {0,   64,  192, 256, 320, 384, 448,
+                                        512, 576, 640, 704, 768, 832};
+const int *const grpc_stats_histo_bucket_boundaries[13] = {
     grpc_stats_table_0, grpc_stats_table_2, grpc_stats_table_4,
     grpc_stats_table_6, grpc_stats_table_4, grpc_stats_table_4,
     grpc_stats_table_6, grpc_stats_table_4, grpc_stats_table_6,
     grpc_stats_table_6, grpc_stats_table_6, grpc_stats_table_6,
-    grpc_stats_table_6, grpc_stats_table_8};
-void (*const grpc_stats_inc_histogram[14])(grpc_exec_ctx *exec_ctx, int x) = {
+    grpc_stats_table_8};
+void (*const grpc_stats_inc_histogram[13])(grpc_exec_ctx *exec_ctx, int x) = {
     grpc_stats_inc_call_initial_size,
     grpc_stats_inc_poll_events_returned,
     grpc_stats_inc_tcp_write_size,
@@ -731,5 +684,4 @@ void (*const grpc_stats_inc_histogram[14])(grpc_exec_ctx *exec_ctx, int x) = {
     grpc_stats_inc_http2_send_message_per_write,
     grpc_stats_inc_http2_send_trailing_metadata_per_write,
     grpc_stats_inc_http2_send_flowctl_per_write,
-    grpc_stats_inc_executor_closures_per_wakeup,
     grpc_stats_inc_server_cqs_checked};
diff --git a/src/core/lib/debug/stats_data.h b/src/core/lib/debug/stats_data.h
index 6c0ad30543f..28dab00117b 100644
--- a/src/core/lib/debug/stats_data.h
+++ b/src/core/lib/debug/stats_data.h
@@ -111,8 +111,6 @@ typedef enum {
   GRPC_STATS_COUNTER_EXECUTOR_WAKEUP_INITIATED,
   GRPC_STATS_COUNTER_EXECUTOR_QUEUE_DRAINED,
   GRPC_STATS_COUNTER_EXECUTOR_PUSH_RETRIES,
-  GRPC_STATS_COUNTER_EXECUTOR_THREADS_CREATED,
-  GRPC_STATS_COUNTER_EXECUTOR_THREADS_USED,
   GRPC_STATS_COUNTER_SERVER_REQUESTED_CALLS,
   GRPC_STATS_COUNTER_SERVER_SLOWPATH_REQUESTS_QUEUED,
   GRPC_STATS_COUNTER_COUNT
@@ -132,7 +130,6 @@ typedef enum {
   GRPC_STATS_HISTOGRAM_HTTP2_SEND_MESSAGE_PER_WRITE,
   GRPC_STATS_HISTOGRAM_HTTP2_SEND_TRAILING_METADATA_PER_WRITE,
   GRPC_STATS_HISTOGRAM_HTTP2_SEND_FLOWCTL_PER_WRITE,
-  GRPC_STATS_HISTOGRAM_EXECUTOR_CLOSURES_PER_WAKEUP,
   GRPC_STATS_HISTOGRAM_SERVER_CQS_CHECKED,
   GRPC_STATS_HISTOGRAM_COUNT
 } grpc_stats_histograms;
@@ -163,11 +160,9 @@ typedef enum {
   GRPC_STATS_HISTOGRAM_HTTP2_SEND_TRAILING_METADATA_PER_WRITE_BUCKETS = 64,
   GRPC_STATS_HISTOGRAM_HTTP2_SEND_FLOWCTL_PER_WRITE_FIRST_SLOT = 768,
   GRPC_STATS_HISTOGRAM_HTTP2_SEND_FLOWCTL_PER_WRITE_BUCKETS = 64,
-  GRPC_STATS_HISTOGRAM_EXECUTOR_CLOSURES_PER_WAKEUP_FIRST_SLOT = 832,
-  GRPC_STATS_HISTOGRAM_EXECUTOR_CLOSURES_PER_WAKEUP_BUCKETS = 64,
-  GRPC_STATS_HISTOGRAM_SERVER_CQS_CHECKED_FIRST_SLOT = 896,
+  GRPC_STATS_HISTOGRAM_SERVER_CQS_CHECKED_FIRST_SLOT = 832,
   GRPC_STATS_HISTOGRAM_SERVER_CQS_CHECKED_BUCKETS = 8,
-  GRPC_STATS_HISTOGRAM_BUCKETS = 904
+  GRPC_STATS_HISTOGRAM_BUCKETS = 840
 } grpc_stats_histogram_constants;
 #define GRPC_STATS_INC_CLIENT_CALLS_CREATED(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_CLIENT_CALLS_CREATED)
@@ -417,11 +412,6 @@ typedef enum {
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_EXECUTOR_QUEUE_DRAINED)
 #define GRPC_STATS_INC_EXECUTOR_PUSH_RETRIES(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_EXECUTOR_PUSH_RETRIES)
-#define GRPC_STATS_INC_EXECUTOR_THREADS_CREATED(exec_ctx) \
-  GRPC_STATS_INC_COUNTER((exec_ctx),                      \
-                         GRPC_STATS_COUNTER_EXECUTOR_THREADS_CREATED)
-#define GRPC_STATS_INC_EXECUTOR_THREADS_USED(exec_ctx) \
-  GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_EXECUTOR_THREADS_USED)
 #define GRPC_STATS_INC_SERVER_REQUESTED_CALLS(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_SERVER_REQUESTED_CALLS)
 #define GRPC_STATS_INC_SERVER_SLOWPATH_REQUESTS_QUEUED(exec_ctx) \
@@ -468,17 +458,13 @@ void grpc_stats_inc_http2_send_trailing_metadata_per_write(
   grpc_stats_inc_http2_send_flowctl_per_write((exec_ctx), (int)(value))
 void grpc_stats_inc_http2_send_flowctl_per_write(grpc_exec_ctx *exec_ctx,
                                                  int x);
-#define GRPC_STATS_INC_EXECUTOR_CLOSURES_PER_WAKEUP(exec_ctx, value) \
-  grpc_stats_inc_executor_closures_per_wakeup((exec_ctx), (int)(value))
-void grpc_stats_inc_executor_closures_per_wakeup(grpc_exec_ctx *exec_ctx,
-                                                 int x);
 #define GRPC_STATS_INC_SERVER_CQS_CHECKED(exec_ctx, value) \
   grpc_stats_inc_server_cqs_checked((exec_ctx), (int)(value))
 void grpc_stats_inc_server_cqs_checked(grpc_exec_ctx *exec_ctx, int x);
-extern const int grpc_stats_histo_buckets[14];
-extern const int grpc_stats_histo_start[14];
-extern const int *const grpc_stats_histo_bucket_boundaries[14];
-extern void (*const grpc_stats_inc_histogram[14])(grpc_exec_ctx *exec_ctx,
+extern const int grpc_stats_histo_buckets[13];
+extern const int grpc_stats_histo_start[13];
+extern const int *const grpc_stats_histo_bucket_boundaries[13];
+extern void (*const grpc_stats_inc_histogram[13])(grpc_exec_ctx *exec_ctx,
                                                   int x);
 
 #endif /* GRPC_CORE_LIB_DEBUG_STATS_DATA_H */
diff --git a/src/core/lib/debug/stats_data.yaml b/src/core/lib/debug/stats_data.yaml
index de575f01c73..b5c15ff55c0 100644
--- a/src/core/lib/debug/stats_data.yaml
+++ b/src/core/lib/debug/stats_data.yaml
@@ -259,14 +259,6 @@
 - counter: executor_push_retries
   doc: Number of times we raced and were forced to retry pushing a closure to
        the executor
-- counter: executor_threads_created
-  doc: Size of the backing thread pool for overflow gRPC Core work
-- counter: executor_threads_used
-  doc: How many executor threads actually got used
-- histogram: executor_closures_per_wakeup
-  max: 1024
-  buckets: 64
-  doc: Number of closures executed each time an executor wakes up
 # server
 - counter: server_requested_calls
   doc: How many calls were requested (not necessarily received) by the server
diff --git a/src/core/lib/debug/stats_data_bq_schema.sql b/src/core/lib/debug/stats_data_bq_schema.sql
index 0611ccaff0e..f96e40c00ef 100644
--- a/src/core/lib/debug/stats_data_bq_schema.sql
+++ b/src/core/lib/debug/stats_data_bq_schema.sql
@@ -84,7 +84,5 @@ executor_scheduled_to_self_per_iteration:FLOAT,
 executor_wakeup_initiated_per_iteration:FLOAT,
 executor_queue_drained_per_iteration:FLOAT,
 executor_push_retries_per_iteration:FLOAT,
-executor_threads_created_per_iteration:FLOAT,
-executor_threads_used_per_iteration:FLOAT,
 server_requested_calls_per_iteration:FLOAT,
 server_slowpath_requests_queued_per_iteration:FLOAT
diff --git a/src/core/lib/iomgr/executor.c b/src/core/lib/iomgr/executor.c
index 2439f15a8a9..892385d7d78 100644
--- a/src/core/lib/iomgr/executor.c
+++ b/src/core/lib/iomgr/executor.c
@@ -32,14 +32,16 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/support/spinlock.h"
 
+#define MAX_DEPTH 2
+
 typedef struct {
   gpr_mu mu;
   gpr_cv cv;
   grpc_closure_list elems;
+  size_t depth;
   bool shutdown;
   bool queued_long_job;
   gpr_thd_id id;
-  grpc_closure_list local_elems;
 } thread_state;
 
 static thread_state *g_thread_state;
@@ -54,35 +56,32 @@ static grpc_tracer_flag executor_trace =
 
 static void executor_thread(void *arg);
 
-static void run_closures(grpc_exec_ctx *exec_ctx, grpc_closure_list *list) {
-  int n = 0;  // number of closures executed
+static size_t run_closures(grpc_exec_ctx *exec_ctx, grpc_closure_list list) {
+  size_t n = 0;
 
-  while (!grpc_closure_list_empty(*list)) {
-    grpc_closure *c = list->head;
-    grpc_closure_list_init(list);
-    while (c != NULL) {
-      grpc_closure *next = c->next_data.next;
-      grpc_error *error = c->error_data.error;
-      if (GRPC_TRACER_ON(executor_trace)) {
+  grpc_closure *c = list.head;
+  while (c != NULL) {
+    grpc_closure *next = c->next_data.next;
+    grpc_error *error = c->error_data.error;
+    if (GRPC_TRACER_ON(executor_trace)) {
 #ifndef NDEBUG
-        gpr_log(GPR_DEBUG, "EXECUTOR: run %p [created by %s:%d]", c,
-                c->file_created, c->line_created);
+      gpr_log(GPR_DEBUG, "EXECUTOR: run %p [created by %s:%d]", c,
+              c->file_created, c->line_created);
 #else
-        gpr_log(GPR_DEBUG, "EXECUTOR: run %p", c);
+      gpr_log(GPR_DEBUG, "EXECUTOR: run %p", c);
 #endif
-      }
+    }
 #ifndef NDEBUG
-      c->scheduled = false;
+    c->scheduled = false;
 #endif
-      n++;
-      c->cb(exec_ctx, c->cb_arg, error);
-      GRPC_ERROR_UNREF(error);
-      c = next;
-      grpc_exec_ctx_flush(exec_ctx);
-    }
+    c->cb(exec_ctx, c->cb_arg, error);
+    GRPC_ERROR_UNREF(error);
+    c = next;
+    n++;
+    grpc_exec_ctx_flush(exec_ctx);
   }
 
-  GRPC_STATS_INC_EXECUTOR_CLOSURES_PER_WAKEUP(exec_ctx, n);
+  return n;
 }
 
 bool grpc_executor_is_threaded() {
@@ -127,7 +126,7 @@ void grpc_executor_set_threading(grpc_exec_ctx *exec_ctx, bool threading) {
     for (size_t i = 0; i < g_max_threads; i++) {
       gpr_mu_destroy(&g_thread_state[i].mu);
       gpr_cv_destroy(&g_thread_state[i].cv);
-      run_closures(exec_ctx, &g_thread_state[i].elems);
+      run_closures(exec_ctx, g_thread_state[i].elems);
     }
     gpr_free(g_thread_state);
     gpr_tls_destroy(&g_this_thread_state);
@@ -151,14 +150,14 @@ static void executor_thread(void *arg) {
   grpc_exec_ctx exec_ctx =
       GRPC_EXEC_CTX_INITIALIZER(0, grpc_never_ready_to_finish, NULL);
 
-  GRPC_STATS_INC_EXECUTOR_THREADS_CREATED(&exec_ctx);
-
-  bool used = false;
+  size_t subtract_depth = 0;
   for (;;) {
     if (GRPC_TRACER_ON(executor_trace)) {
-      gpr_log(GPR_DEBUG, "EXECUTOR[%d]: step", (int)(ts - g_thread_state));
+      gpr_log(GPR_DEBUG, "EXECUTOR[%d]: step (sub_depth=%" PRIdPTR ")",
+              (int)(ts - g_thread_state), subtract_depth);
     }
     gpr_mu_lock(&ts->mu);
+    ts->depth -= subtract_depth;
     while (grpc_closure_list_empty(ts->elems) && !ts->shutdown) {
       ts->queued_long_job = false;
       gpr_cv_wait(&ts->cv, &ts->mu, gpr_inf_future(GPR_CLOCK_REALTIME));
@@ -171,20 +170,15 @@ static void executor_thread(void *arg) {
       gpr_mu_unlock(&ts->mu);
       break;
     }
-    if (!used) {
-      GRPC_STATS_INC_EXECUTOR_THREADS_USED(&exec_ctx);
-      used = true;
-    }
     GRPC_STATS_INC_EXECUTOR_QUEUE_DRAINED(&exec_ctx);
-    GPR_ASSERT(grpc_closure_list_empty(ts->local_elems));
-    ts->local_elems = ts->elems;
+    grpc_closure_list exec = ts->elems;
     ts->elems = (grpc_closure_list)GRPC_CLOSURE_LIST_INIT;
     gpr_mu_unlock(&ts->mu);
     if (GRPC_TRACER_ON(executor_trace)) {
       gpr_log(GPR_DEBUG, "EXECUTOR[%d]: execute", (int)(ts - g_thread_state));
     }
 
-    run_closures(&exec_ctx, &ts->local_elems);
+    subtract_depth = run_closures(&exec_ctx, exec);
   }
   grpc_exec_ctx_finish(&exec_ctx);
 }
@@ -217,10 +211,6 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
       ts = &g_thread_state[GPR_HASH_POINTER(exec_ctx, cur_thread_count)];
     } else {
       GRPC_STATS_INC_EXECUTOR_SCHEDULED_TO_SELF(exec_ctx);
-      if (is_short) {
-        grpc_closure_list_append(&ts->local_elems, closure, error);
-        return;
-      }
     }
     thread_state *orig_ts = ts;
 
@@ -260,7 +250,8 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
         gpr_cv_signal(&ts->cv);
       }
       grpc_closure_list_append(&ts->elems, closure, error);
-      try_new_thread = ts->elems.head != closure &&
+      ts->depth++;
+      try_new_thread = ts->depth > MAX_DEPTH &&
                        cur_thread_count < g_max_threads && !ts->shutdown;
       if (!is_short) ts->queued_long_job = true;
       gpr_mu_unlock(&ts->mu);
diff --git a/src/core/lib/security/credentials/composite/composite_credentials.c b/src/core/lib/security/credentials/composite/composite_credentials.c
index 09fd60a12c2..b67ff48d0f4 100644
--- a/src/core/lib/security/credentials/composite/composite_credentials.c
+++ b/src/core/lib/security/credentials/composite/composite_credentials.c
@@ -87,6 +87,7 @@ static bool composite_call_get_request_metadata(
   ctx->on_request_metadata = on_request_metadata;
   GRPC_CLOSURE_INIT(&ctx->internal_on_request_metadata,
                     composite_call_metadata_cb, ctx, grpc_schedule_on_exec_ctx);
+  bool synchronous = true;
   while (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
     grpc_call_credentials *inner_creds =
         ctx->composite_creds->inner.creds_array[ctx->creds_index++];
@@ -95,19 +96,12 @@ static bool composite_call_get_request_metadata(
             ctx->md_array, &ctx->internal_on_request_metadata, error)) {
       if (*error != GRPC_ERROR_NONE) break;
     } else {
+      synchronous = false;  // Async return.
       break;
     }
   }
-  // If we got through all creds synchronously or we got a synchronous
-  // error on one of them, return synchronously.
-  if (ctx->creds_index == ctx->composite_creds->inner.num_creds ||
-      *error != GRPC_ERROR_NONE) {
-    gpr_free(ctx);
-    return true;
-  }
-  // At least one inner cred is returning asynchronously, so we'll
-  // return asynchronously as well.
-  return false;
+  if (synchronous) gpr_free(ctx);
+  return synchronous;
 }
 
 static void composite_call_cancel_get_request_metadata(
diff --git a/src/cpp/common/channel_arguments.cc b/src/cpp/common/channel_arguments.cc
index f130aecd4b5..f89f5f1f03d 100644
--- a/src/cpp/common/channel_arguments.cc
+++ b/src/cpp/common/channel_arguments.cc
@@ -86,6 +86,10 @@ void ChannelArguments::SetCompressionAlgorithm(
   SetInt(GRPC_COMPRESSION_CHANNEL_DEFAULT_ALGORITHM, algorithm);
 }
 
+void ChannelArguments::SetGrpclbFallbackTimeout(int fallback_timeout) {
+  SetInt(GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS, fallback_timeout);
+}
+
 void ChannelArguments::SetSocketMutator(grpc_socket_mutator* mutator) {
   if (!mutator) {
     return;
diff --git a/src/python/grpcio/support.py b/src/python/grpcio/support.py
index 510bf422a07..f2395eb26c2 100644
--- a/src/python/grpcio/support.py
+++ b/src/python/grpcio/support.py
@@ -94,7 +94,7 @@ def diagnose_attribute_error(build_ext, error):
 
 _ERROR_DIAGNOSES = {
     errors.CompileError: diagnose_compile_error,
-    AttributeError: diagnose_attribute_error
+    AttributeError: diagnose_attribute_error,
 }
 
 
@@ -102,8 +102,10 @@ def diagnose_build_ext_error(build_ext, error, formatted):
     diagnostic = _ERROR_DIAGNOSES.get(type(error))
     if diagnostic is None:
         raise commands.CommandError(
-            "\n\nWe could not diagnose your build failure. Please file an issue at "
-            "http://www.github.com/grpc/grpc with `[Python install]` in the title."
-            "\n\n{}".format(formatted))
+            "\n\nWe could not diagnose your build failure. If you are unable to "
+            "proceed, please file an issue at http://www.github.com/grpc/grpc "
+            "with `[Python install]` in the title; please attach the whole log "
+            "(including everything that may have appeared above the Python "
+            "backtrace).\n\n{}".format(formatted))
     else:
         diagnostic(build_ext, error)
diff --git a/src/ruby/lib/grpc/google_rpc_status_utils.rb b/src/ruby/lib/grpc/google_rpc_status_utils.rb
index fdadd6b76e4..f253b082b63 100644
--- a/src/ruby/lib/grpc/google_rpc_status_utils.rb
+++ b/src/ruby/lib/grpc/google_rpc_status_utils.rb
@@ -19,10 +19,17 @@ require 'google/rpc/status_pb'
 module GRPC
   # GoogleRpcStatusUtils provides utilities to convert between a
   # GRPC::Core::Status and a deserialized Google::Rpc::Status proto
+  # Returns nil if the grpc-status-details-bin trailer could not be
+  # converted to a GoogleRpcStatus due to the server not providing
+  # the necessary trailers.
+  # Raises an error if the server did provide the necessary trailers
+  # but they fail to deseriliaze into a GoogleRpcStatus protobuf.
   class GoogleRpcStatusUtils
     def self.extract_google_rpc_status(status)
       fail ArgumentError, 'bad type' unless status.is_a? Struct::Status
-      Google::Rpc::Status.decode(status.metadata['grpc-status-details-bin'])
+      grpc_status_details_bin_trailer = 'grpc-status-details-bin'
+      return nil if status.metadata[grpc_status_details_bin_trailer].nil?
+      Google::Rpc::Status.decode(status.metadata[grpc_status_details_bin_trailer])
     end
   end
 end
diff --git a/src/ruby/spec/google_rpc_status_utils_spec.rb b/src/ruby/spec/google_rpc_status_utils_spec.rb
index fe221c30ddd..6f2a06b1d93 100644
--- a/src/ruby/spec/google_rpc_status_utils_spec.rb
+++ b/src/ruby/spec/google_rpc_status_utils_spec.rb
@@ -31,12 +31,11 @@ describe 'conversion from a status struct to a google protobuf status' do
     expect(exception.message.include?('bad type')).to be true
   end
 
-  it 'fails with some error if the header key is missing' do
+  it 'returns nil if the header key is missing' do
     status = Struct::Status.new(1, 'details', key: 'val')
     expect(status.metadata.nil?).to be false
-    expect do
-      GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(status)
-    end.to raise_error(StandardError)
+    expect(GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+             status)).to be(nil)
   end
 
   it 'fails with some error if the header key fails to deserialize' do
@@ -221,3 +220,73 @@ describe 'receving a google rpc status from a remote endpoint' do
              status_from_exception)).to eq(rpc_status)
   end
 end
+
+# A test service that fails without explicitly setting the
+# grpc-status-details-bin trailer. Tests assumptions about value
+# of grpc-status-details-bin on the client side when the trailer wasn't
+# set explicitly.
+class NoStatusDetailsBinTestService
+  include GRPC::GenericService
+  rpc :an_rpc, EchoMsg, EchoMsg
+
+  def an_rpc(_, _)
+    fail GRPC::Unknown
+  end
+end
+
+NoStatusDetailsBinTestServiceStub = NoStatusDetailsBinTestService.rpc_stub_class
+
+describe 'when the endpoint doesnt send grpc-status-details-bin' do
+  def start_server
+    @srv = GRPC::RpcServer.new(pool_size: 1)
+    @server_port = @srv.add_http2_port('localhost:0',
+                                       :this_port_is_insecure)
+    @srv.handle(NoStatusDetailsBinTestService)
+    @server_thd = Thread.new { @srv.run }
+    @srv.wait_till_running
+  end
+
+  def stop_server
+    expect(@srv.stopped?).to be(false)
+    @srv.stop
+    @server_thd.join
+    expect(@srv.stopped?).to be(true)
+  end
+
+  before(:each) do
+    start_server
+  end
+
+  after(:each) do
+    stop_server
+  end
+
+  it 'should receive nil when we extract try to extract a google '\
+    'rpc status from a BadStatus exception that didnt have it' do
+    stub = NoStatusDetailsBinTestServiceStub.new("localhost:#{@server_port}",
+                                                 :this_channel_is_insecure)
+    begin
+      stub.an_rpc(EchoMsg.new)
+    rescue GRPC::Unknown => e
+      rpc_status = GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+        e.to_status)
+    end
+    expect(rpc_status).to be(nil)
+  end
+
+  it 'should receive nil when we extract try to extract a google '\
+    'rpc status from an op views status object that didnt have it' do
+    stub = NoStatusDetailsBinTestServiceStub.new("localhost:#{@server_port}",
+                                                 :this_channel_is_insecure)
+    op = stub.an_rpc(EchoMsg.new, return_op: true)
+    begin
+      op.execute
+    rescue GRPC::Unknown => e
+      status_from_exception = e.to_status
+    end
+    expect(GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+             status_from_exception)).to be(nil)
+    expect(GRPC::GoogleRpcStatusUtils.extract_google_rpc_status(
+             op.status)).to be nil
+  end
+end
diff --git a/templates/test/cpp/naming/create_private_dns_zone.sh.template b/templates/test/cpp/naming/create_private_dns_zone.sh.template
new file mode 100644
index 00000000000..14324b098c5
--- /dev/null
+++ b/templates/test/cpp/naming/create_private_dns_zone.sh.template
@@ -0,0 +1,4 @@
+%YAML 1.2
+--- |
+  <%namespace file="create_private_dns_zone_defs.include" import="*"/>\
+  ${create_private_dns_zone(resolver_gce_integration_tests_zone_id, resolver_tests_common_zone_name)}
diff --git a/templates/test/cpp/naming/create_private_dns_zone_defs.include b/templates/test/cpp/naming/create_private_dns_zone_defs.include
new file mode 100644
index 00000000000..465dd6394bf
--- /dev/null
+++ b/templates/test/cpp/naming/create_private_dns_zone_defs.include
@@ -0,0 +1,32 @@
+<%def name="create_private_dns_zone(resolver_gce_integration_tests_zone_id, resolver_tests_common_zone_name)">#!/bin/bash
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is auto-generated
+
+set -ex
+
+cd $(dirname $0)/../../..
+
+gcloud alpha dns managed-zones create \\
+
+  ${resolver_gce_integration_tests_zone_id} \\
+
+  --dns-name=${resolver_tests_common_zone_name} \\
+
+  --description="GCE-DNS-private-zone-for-GRPC-testing" \\
+
+  --visibility=private \\
+
+  --networks=default</%def>
diff --git a/templates/test/cpp/naming/private_dns_zone_init.sh.template b/templates/test/cpp/naming/private_dns_zone_init.sh.template
new file mode 100644
index 00000000000..d5ffd04add1
--- /dev/null
+++ b/templates/test/cpp/naming/private_dns_zone_init.sh.template
@@ -0,0 +1,4 @@
+%YAML 1.2
+--- |
+  <%namespace file="private_dns_zone_init_defs.include" import="*"/>\
+  ${private_dns_zone_init(all_integration_test_records, resolver_gce_integration_tests_zone_id, resolver_tests_common_zone_name)}
diff --git a/templates/test/cpp/naming/private_dns_zone_init_defs.include b/templates/test/cpp/naming/private_dns_zone_init_defs.include
new file mode 100644
index 00000000000..06bc8adb94e
--- /dev/null
+++ b/templates/test/cpp/naming/private_dns_zone_init_defs.include
@@ -0,0 +1,40 @@
+<%def name="private_dns_zone_init(records,resolver_gce_integration_tests_zone_id,resolver_tests_common_zone_name)">#!/bin/bash
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is auto-generated
+
+set -ex
+
+cd $(dirname $0)/../../..
+
+gcloud dns record-sets transaction start -z=${resolver_gce_integration_tests_zone_id}
+
+% for r in records:
+gcloud dns record-sets transaction add \\
+
+  -z=${resolver_gce_integration_tests_zone_id} \\
+
+  --name=${r['name']}.${resolver_tests_common_zone_name} \\
+
+  --type=${r['type']} \\
+
+  --ttl=${r['ttl']} \\
+
+  ${r['data']}
+
+% endfor
+gcloud dns record-sets transaction describe -z=${resolver_gce_integration_tests_zone_id}
+gcloud dns record-sets transaction execute -z=${resolver_gce_integration_tests_zone_id}
+gcloud dns record-sets list -z=${resolver_gce_integration_tests_zone_id}</%def>
diff --git a/templates/test/cpp/naming/resolver_gce_integration_tests_defs.include b/templates/test/cpp/naming/resolver_gce_integration_tests_defs.include
new file mode 100644
index 00000000000..2413ec57d09
--- /dev/null
+++ b/templates/test/cpp/naming/resolver_gce_integration_tests_defs.include
@@ -0,0 +1,64 @@
+<%def name="resolver_gce_integration_tests(tests, records, resolver_tests_common_zone_name)">#!/bin/bash
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is auto-generated
+
+set -ex
+
+if [[ "$GRPC_DNS_RESOLVER" == "" ]]; then
+  export GRPC_DNS_RESOLVER=ares
+elif [[ "$GRPC_DNS_RESOLVER" != ares ]]; then
+  echo "Unexpected: GRPC_DNS_RESOLVER=$GRPC_DNS_RESOLVER. This test only works with c-ares resolver"
+  exit 1
+fi
+
+cd $(dirname $0)/../../..
+
+if [[ "$CONFIG" == "" ]]; then
+  export CONFIG=opt
+fi
+make resolver_component_test
+echo "Sanity check DNS records are resolveable with dig:"
+EXIT_CODE=0
+
+% for r in records:
+ONE_FAILED=0
+dig ${r['type']} ${r['name']}.${resolver_tests_common_zone_name} | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig ${r['type']} ${r['name']}.${resolver_tests_common_zone_name} FAILED"
+  exit 1
+fi
+
+% endfor
+echo "Sanity check PASSED. Run resolver tests:"
+
+% for test in tests:
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \\
+
+  --target_name='${test['target_name']}' \\
+
+  --expected_addrs='${test['expected_addrs']}' \\
+
+  --expected_chosen_service_config='${test['expected_chosen_service_config']}' \\
+
+  --expected_lb_policy='${test['expected_lb_policy']}' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: ${test['target_name']} FAILED"
+  EXIT_CODE=1
+fi
+
+% endfor
+exit $EXIT_CODE</%def>
diff --git a/templates/test/cpp/naming/resolver_gce_integration_tests_runner.sh.template b/templates/test/cpp/naming/resolver_gce_integration_tests_runner.sh.template
new file mode 100644
index 00000000000..c728784d29a
--- /dev/null
+++ b/templates/test/cpp/naming/resolver_gce_integration_tests_runner.sh.template
@@ -0,0 +1,4 @@
+%YAML 1.2
+--- |
+  <%namespace file="resolver_gce_integration_tests_defs.include" import="*"/>\
+  ${resolver_gce_integration_tests(resolver_gce_integration_test_cases, all_integration_test_records, resolver_tests_common_zone_name)}
diff --git a/test/core/bad_client/bad_client.c b/test/core/bad_client/bad_client.c
index 383d1240cb0..fff0c793ed6 100644
--- a/test/core/bad_client/bad_client.c
+++ b/test/core/bad_client/bad_client.c
@@ -134,9 +134,12 @@ void grpc_run_bad_client_test(
   grpc_endpoint_write(&exec_ctx, sfd.client, &outgoing, &done_write_closure);
   grpc_exec_ctx_finish(&exec_ctx);
 
-  /* Await completion */
-  GPR_ASSERT(
-      gpr_event_wait(&a.done_write, grpc_timeout_seconds_to_deadline(5)));
+  /* Await completion, unless the request is large and write may not finish
+   * before the peer shuts down. */
+  if (!(flags & GRPC_BAD_CLIENT_LARGE_REQUEST)) {
+    GPR_ASSERT(
+        gpr_event_wait(&a.done_write, grpc_timeout_seconds_to_deadline(5)));
+  }
 
   if (flags & GRPC_BAD_CLIENT_DISCONNECT) {
     grpc_endpoint_shutdown(
@@ -186,6 +189,8 @@ void grpc_run_bad_client_test(
     grpc_exec_ctx_finish(&exec_ctx);
   }
 
+  GPR_ASSERT(
+      gpr_event_wait(&a.done_write, grpc_timeout_seconds_to_deadline(1)));
   shutdown_cq = grpc_completion_queue_create_for_pluck(NULL);
   grpc_server_shutdown_and_notify(a.server, shutdown_cq, NULL);
   GPR_ASSERT(grpc_completion_queue_pluck(
diff --git a/test/core/bad_client/bad_client.h b/test/core/bad_client/bad_client.h
index 22f1a3abc7a..a5b01f7f2c1 100644
--- a/test/core/bad_client/bad_client.h
+++ b/test/core/bad_client/bad_client.h
@@ -37,6 +37,7 @@ typedef bool (*grpc_bad_client_client_stream_validator)(
     grpc_slice_buffer *incoming);
 
 #define GRPC_BAD_CLIENT_DISCONNECT 1
+#define GRPC_BAD_CLIENT_LARGE_REQUEST 2
 
 /* Test runner.
 
diff --git a/test/core/bad_client/tests/window_overflow.c b/test/core/bad_client/tests/window_overflow.c
index 1f29bd32fbd..18c647ad8a7 100644
--- a/test/core/bad_client/tests/window_overflow.c
+++ b/test/core/bad_client/tests/window_overflow.c
@@ -90,7 +90,8 @@ int main(int argc, char **argv) {
       addbuf(message, sizeof(message));
     }
   }
-  grpc_run_bad_client_test(verifier, NULL, g_buffer, g_count, 0);
+  grpc_run_bad_client_test(verifier, NULL, g_buffer, g_count,
+                           GRPC_BAD_CLIENT_LARGE_REQUEST);
   gpr_free(g_buffer);
 
   return 0;
diff --git a/test/core/iomgr/pollset_set_test.c b/test/core/iomgr/pollset_set_test.c
index 70efca8b16f..5750ac0f4b3 100644
--- a/test/core/iomgr/pollset_set_test.c
+++ b/test/core/iomgr/pollset_set_test.c
@@ -24,7 +24,6 @@
 #include <string.h>
 #include <unistd.h>
 
-#include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/useful.h>
@@ -434,7 +433,8 @@ int main(int argc, char **argv) {
   const char *poll_strategy = grpc_get_poll_strategy_name();
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_test_init(argc, argv);
-  grpc_init();
+  grpc_iomgr_init(&exec_ctx);
+  grpc_iomgr_start(&exec_ctx);
 
   if (poll_strategy != NULL &&
       (strcmp(poll_strategy, "epoll") == 0 ||
@@ -449,8 +449,8 @@ int main(int argc, char **argv) {
             poll_strategy);
   }
 
+  grpc_iomgr_shutdown(&exec_ctx);
   grpc_exec_ctx_finish(&exec_ctx);
-  grpc_shutdown();
   return 0;
 }
 #else /* defined(GRPC_LINUX_EPOLL) */
diff --git a/test/core/tsi/transport_security_test_lib.c b/test/core/tsi/transport_security_test_lib.c
index 7d66e110f2e..329b2371bf1 100644
--- a/test/core/tsi/transport_security_test_lib.c
+++ b/test/core/tsi/transport_security_test_lib.c
@@ -23,9 +23,26 @@
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/thd.h>
 #include "src/core/lib/security/transport/tsi_error.h"
 #include "test/core/tsi/transport_security_test_lib.h"
 
+static void notification_signal(tsi_test_fixture *fixture) {
+  gpr_mu_lock(&fixture->mu);
+  fixture->notified = true;
+  gpr_cv_signal(&fixture->cv);
+  gpr_mu_unlock(&fixture->mu);
+}
+
+static void notification_wait(tsi_test_fixture *fixture) {
+  gpr_mu_lock(&fixture->mu);
+  while (!fixture->notified) {
+    gpr_cv_wait(&fixture->cv, &fixture->mu, gpr_inf_future(GPR_CLOCK_REALTIME));
+  }
+  fixture->notified = false;
+  gpr_mu_unlock(&fixture->mu);
+}
+
 typedef struct handshaker_args {
   tsi_test_fixture *fixture;
   unsigned char *handshake_buffer;
@@ -273,9 +290,11 @@ grpc_error *on_handshake_next_done(tsi_result result, void *user_data,
   /* Read more data if we need to. */
   if (result == TSI_INCOMPLETE_DATA) {
     GPR_ASSERT(bytes_to_send_size == 0);
+    notification_signal(fixture);
     return error;
   }
   if (result != TSI_OK) {
+    notification_signal(fixture);
     return grpc_set_tsi_error_result(
         GRPC_ERROR_CREATE_FROM_STATIC_STRING("Handshake failed"), result);
   }
@@ -295,6 +314,7 @@ grpc_error *on_handshake_next_done(tsi_result result, void *user_data,
   if (handshaker_result != NULL) {
     maybe_append_unused_bytes(args);
   }
+  notification_signal(fixture);
   return error;
 }
 
@@ -345,7 +365,11 @@ static void do_handshaker_next(handshaker_args *args) {
   if (result != TSI_ASYNC) {
     args->error = on_handshake_next_done(result, args, bytes_to_send,
                                          bytes_to_send_size, handshaker_result);
+    if (args->error != GRPC_ERROR_NONE) {
+      return;
+    }
   }
+  notification_wait(fixture);
 }
 
 void tsi_test_do_handshake(tsi_test_fixture *fixture) {
@@ -532,6 +556,9 @@ void tsi_test_fixture_init(tsi_test_fixture *fixture) {
   fixture->bytes_read_from_server_channel = 0;
   fixture->test_unused_bytes = true;
   fixture->has_client_finished_first = false;
+  gpr_mu_init(&fixture->mu);
+  gpr_cv_init(&fixture->cv);
+  fixture->notified = false;
 }
 
 void tsi_test_fixture_destroy(tsi_test_fixture *fixture) {
@@ -546,5 +573,7 @@ void tsi_test_fixture_destroy(tsi_test_fixture *fixture) {
   GPR_ASSERT(fixture->vtable != NULL);
   GPR_ASSERT(fixture->vtable->destruct != NULL);
   fixture->vtable->destruct(fixture);
+  gpr_mu_destroy(&fixture->mu);
+  gpr_cv_destroy(&fixture->cv);
   gpr_free(fixture);
 }
diff --git a/test/core/tsi/transport_security_test_lib.h b/test/core/tsi/transport_security_test_lib.h
index 8ae2024ee49..ed8ff856dfa 100644
--- a/test/core/tsi/transport_security_test_lib.h
+++ b/test/core/tsi/transport_security_test_lib.h
@@ -21,6 +21,10 @@
 
 #include "src/core/tsi/transport_security_interface.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define TSI_TEST_TINY_HANDSHAKE_BUFFER_SIZE 32
 #define TSI_TEST_SMALL_HANDSHAKE_BUFFER_SIZE 128
 #define TSI_TEST_SMALL_READ_BUFFER_ALLOCATED_SIZE 41
@@ -56,10 +60,10 @@ typedef struct tsi_test_fixture_vtable {
   void (*setup_handshakers)(tsi_test_fixture *fixture);
   void (*check_handshaker_peers)(tsi_test_fixture *fixture);
   void (*destruct)(tsi_test_fixture *fixture);
-} tranport_security_test_vtable;
+} tsi_test_fixture_vtable;
 
 struct tsi_test_fixture {
-  const struct tsi_test_fixture_vtable *vtable;
+  const tsi_test_fixture_vtable *vtable;
   /* client/server TSI handshaker used to perform TSI handshakes, and will get
      instantiated during the call to setup_handshakers. */
   tsi_handshaker *client_handshaker;
@@ -95,6 +99,13 @@ struct tsi_test_fixture {
      (https://github.com/grpc/grpc/issues/12164).
   */
   bool test_unused_bytes;
+  /* These objects will be used coordinate client/server handshakers with TSI
+     thread to perform TSI handshakes in an asynchronous manner (for GTS TSI
+     implementations).
+  */
+  gpr_cv cv;
+  gpr_mu mu;
+  bool notified;
 };
 
 struct tsi_test_frame_protector_config {
@@ -162,4 +173,8 @@ void tsi_test_do_handshake(tsi_test_fixture *fixture);
    the client and server switching its role. */
 void tsi_test_do_round_trip(tsi_test_fixture *fixture);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif  // GRPC_TEST_CORE_TSI_TRANSPORT_SECURITY_TEST_LIB_H_
diff --git a/test/cpp/end2end/grpclb_end2end_test.cc b/test/cpp/end2end/grpclb_end2end_test.cc
index 77ed1552923..f73a9c17917 100644
--- a/test/cpp/end2end/grpclb_end2end_test.cc
+++ b/test/cpp/end2end/grpclb_end2end_test.cc
@@ -368,8 +368,9 @@ class GrpclbEnd2endTest : public ::testing::Test {
     grpc_fake_resolver_response_generator_unref(response_generator_);
   }
 
-  void ResetStub() {
+  void ResetStub(int fallback_timeout = 0) {
     ChannelArguments args;
+    args.SetGrpclbFallbackTimeout(fallback_timeout);
     args.SetPointer(GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,
                     response_generator_);
     std::ostringstream uri;
@@ -470,10 +471,10 @@ class GrpclbEnd2endTest : public ::testing::Test {
     grpc_exec_ctx_finish(&exec_ctx);
   }
 
-  const std::vector<int> GetBackendPorts() const {
+  const std::vector<int> GetBackendPorts(const size_t start_index = 0) const {
     std::vector<int> backend_ports;
-    for (const auto& bs : backend_servers_) {
-      backend_ports.push_back(bs.port_);
+    for (size_t i = start_index; i < backend_servers_.size(); ++i) {
+      backend_ports.push_back(backend_servers_[i].port_);
     }
     return backend_ports;
   }
@@ -642,6 +643,177 @@ TEST_F(SingleBalancerTest, InitiallyEmptyServerlist) {
   EXPECT_EQ("grpclb", channel_->GetLoadBalancingPolicyName());
 }
 
+TEST_F(SingleBalancerTest, Fallback) {
+  const int kFallbackTimeoutMs = 200 * grpc_test_slowdown_factor();
+  const int kServerlistDelayMs = 500 * grpc_test_slowdown_factor();
+  const size_t kNumBackendInResolution = backends_.size() / 2;
+
+  ResetStub(kFallbackTimeoutMs);
+  std::vector<AddressData> addresses;
+  addresses.emplace_back(AddressData{balancer_servers_[0].port_, true, ""});
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    addresses.emplace_back(AddressData{backend_servers_[i].port_, false, ""});
+  }
+  SetNextResolution(addresses);
+
+  // Send non-empty serverlist only after kServerlistDelayMs.
+  ScheduleResponseForBalancer(
+      0, BalancerServiceImpl::BuildResponseForBackends(
+             GetBackendPorts(kNumBackendInResolution /* start_index */), {}),
+      kServerlistDelayMs);
+
+  // Wait until all the fallback backends are reachable.
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    WaitForBackend(i);
+  }
+
+  // The first request.
+  gpr_log(GPR_INFO, "========= BEFORE FIRST BATCH ==========");
+  CheckRpcSendOk(kNumBackendInResolution);
+  gpr_log(GPR_INFO, "========= DONE WITH FIRST BATCH ==========");
+
+  // Fallback is used: each backend returned by the resolver should have
+  // gotten one request.
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    EXPECT_EQ(1U, backend_servers_[i].service_->request_count());
+  }
+  for (size_t i = kNumBackendInResolution; i < backends_.size(); ++i) {
+    EXPECT_EQ(0U, backend_servers_[i].service_->request_count());
+  }
+
+  // Wait until the serverlist reception has been processed and all backends
+  // in the serverlist are reachable.
+  for (size_t i = kNumBackendInResolution; i < backends_.size(); ++i) {
+    WaitForBackend(i);
+  }
+
+  // Send out the second request.
+  gpr_log(GPR_INFO, "========= BEFORE SECOND BATCH ==========");
+  CheckRpcSendOk(backends_.size() - kNumBackendInResolution);
+  gpr_log(GPR_INFO, "========= DONE WITH SECOND BATCH ==========");
+
+  // Serverlist is used: each backend returned by the balancer should
+  // have gotten one request.
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    EXPECT_EQ(0U, backend_servers_[i].service_->request_count());
+  }
+  for (size_t i = kNumBackendInResolution; i < backends_.size(); ++i) {
+    EXPECT_EQ(1U, backend_servers_[i].service_->request_count());
+  }
+
+  balancers_[0]->NotifyDoneWithServerlists();
+  // The balancer got a single request.
+  EXPECT_EQ(1U, balancer_servers_[0].service_->request_count());
+  // and sent a single response.
+  EXPECT_EQ(1U, balancer_servers_[0].service_->response_count());
+}
+
+TEST_F(SingleBalancerTest, FallbackUpdate) {
+  const int kFallbackTimeoutMs = 200 * grpc_test_slowdown_factor();
+  const int kServerlistDelayMs = 500 * grpc_test_slowdown_factor();
+  const size_t kNumBackendInResolution = backends_.size() / 3;
+  const size_t kNumBackendInResolutionUpdate = backends_.size() / 3;
+
+  ResetStub(kFallbackTimeoutMs);
+  std::vector<AddressData> addresses;
+  addresses.emplace_back(AddressData{balancer_servers_[0].port_, true, ""});
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    addresses.emplace_back(AddressData{backend_servers_[i].port_, false, ""});
+  }
+  SetNextResolution(addresses);
+
+  // Send non-empty serverlist only after kServerlistDelayMs.
+  ScheduleResponseForBalancer(
+      0, BalancerServiceImpl::BuildResponseForBackends(
+             GetBackendPorts(kNumBackendInResolution +
+                             kNumBackendInResolutionUpdate /* start_index */),
+             {}),
+      kServerlistDelayMs);
+
+  // Wait until all the fallback backends are reachable.
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    WaitForBackend(i);
+  }
+
+  // The first request.
+  gpr_log(GPR_INFO, "========= BEFORE FIRST BATCH ==========");
+  CheckRpcSendOk(kNumBackendInResolution);
+  gpr_log(GPR_INFO, "========= DONE WITH FIRST BATCH ==========");
+
+  // Fallback is used: each backend returned by the resolver should have
+  // gotten one request.
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    EXPECT_EQ(1U, backend_servers_[i].service_->request_count());
+  }
+  for (size_t i = kNumBackendInResolution; i < backends_.size(); ++i) {
+    EXPECT_EQ(0U, backend_servers_[i].service_->request_count());
+  }
+
+  addresses.clear();
+  addresses.emplace_back(AddressData{balancer_servers_[0].port_, true, ""});
+  for (size_t i = kNumBackendInResolution;
+       i < kNumBackendInResolution + kNumBackendInResolutionUpdate; ++i) {
+    addresses.emplace_back(AddressData{backend_servers_[i].port_, false, ""});
+  }
+  SetNextResolution(addresses);
+
+  // Wait until the resolution update has been processed and all the new
+  // fallback backends are reachable.
+  for (size_t i = kNumBackendInResolution;
+       i < kNumBackendInResolution + kNumBackendInResolutionUpdate; ++i) {
+    WaitForBackend(i);
+  }
+
+  // Send out the second request.
+  gpr_log(GPR_INFO, "========= BEFORE SECOND BATCH ==========");
+  CheckRpcSendOk(kNumBackendInResolutionUpdate);
+  gpr_log(GPR_INFO, "========= DONE WITH SECOND BATCH ==========");
+
+  // The resolution update is used: each backend in the resolution update should
+  // have gotten one request.
+  for (size_t i = 0; i < kNumBackendInResolution; ++i) {
+    EXPECT_EQ(0U, backend_servers_[i].service_->request_count());
+  }
+  for (size_t i = kNumBackendInResolution;
+       i < kNumBackendInResolution + kNumBackendInResolutionUpdate; ++i) {
+    EXPECT_EQ(1U, backend_servers_[i].service_->request_count());
+  }
+  for (size_t i = kNumBackendInResolution + kNumBackendInResolutionUpdate;
+       i < backends_.size(); ++i) {
+    EXPECT_EQ(0U, backend_servers_[i].service_->request_count());
+  }
+
+  // Wait until the serverlist reception has been processed and all backends
+  // in the serverlist are reachable.
+  for (size_t i = kNumBackendInResolution + kNumBackendInResolutionUpdate;
+       i < backends_.size(); ++i) {
+    WaitForBackend(i);
+  }
+
+  // Send out the third request.
+  gpr_log(GPR_INFO, "========= BEFORE THIRD BATCH ==========");
+  CheckRpcSendOk(backends_.size() - kNumBackendInResolution -
+                 kNumBackendInResolutionUpdate);
+  gpr_log(GPR_INFO, "========= DONE WITH THIRD BATCH ==========");
+
+  // Serverlist is used: each backend returned by the balancer should
+  // have gotten one request.
+  for (size_t i = 0;
+       i < kNumBackendInResolution + kNumBackendInResolutionUpdate; ++i) {
+    EXPECT_EQ(0U, backend_servers_[i].service_->request_count());
+  }
+  for (size_t i = kNumBackendInResolution + kNumBackendInResolutionUpdate;
+       i < backends_.size(); ++i) {
+    EXPECT_EQ(1U, backend_servers_[i].service_->request_count());
+  }
+
+  balancers_[0]->NotifyDoneWithServerlists();
+  // The balancer got a single request.
+  EXPECT_EQ(1U, balancer_servers_[0].service_->request_count());
+  // and sent a single response.
+  EXPECT_EQ(1U, balancer_servers_[0].service_->response_count());
+}
+
 TEST_F(SingleBalancerTest, BackendsRestart) {
   const size_t kNumRpcsPerAddress = 100;
   ScheduleResponseForBalancer(
diff --git a/test/cpp/naming/README.md b/test/cpp/naming/README.md
new file mode 100644
index 00000000000..e33184620c0
--- /dev/null
+++ b/test/cpp/naming/README.md
@@ -0,0 +1,43 @@
+# Resolver Tests
+
+This directory has tests and infrastructure for unit tests and GCE
+integration tests of gRPC resolver functionality.
+
+There are two different tests here:
+
+## Resolver unit tests (resolver "component" tests)
+
+These tests run per-change, along with the rest of the grpc unit tests.
+They query a local testing DNS server.
+
+## GCE integration tests
+
+These tests use the same test binary and the same test records
+as the unit tests, but they run against GCE DNS (this is done by
+running the test on a GCE instance and not specifying an authority
+in uris). These tests run in a background job, which needs to be
+actively monitored.
+
+## Making changes to test records
+
+After making a change to `resolver_test_record_groups.yaml`:
+
+1. Increment the "version number" in the `resolver_tests_common_zone_name`
+   DNS zone (this is a yaml field at the top
+   of `resolver_test_record_groups.yaml`).
+
+2. Regenerate projects.
+
+3. From the repo root, run:
+
+```
+$ test/cpp/naming/create_dns_private_zone.sh
+$ test/cpp/naming/private_dns_zone_init.sh
+```
+
+Note that these commands must be ran in environment that
+has access to the grpc-testing GCE project.
+
+If everything runs smoothly, then once the change is merged,
+the GCE DNS integration testing job will transition to the
+new records and continue passing.
diff --git a/test/cpp/naming/create_private_dns_zone.sh b/test/cpp/naming/create_private_dns_zone.sh
new file mode 100755
index 00000000000..3d7520b90a8
--- /dev/null
+++ b/test/cpp/naming/create_private_dns_zone.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is auto-generated
+
+set -ex
+
+cd $(dirname $0)/../../..
+
+gcloud alpha dns managed-zones create \
+  resolver-tests-version-1-grpctestingexp-zone-id \
+  --dns-name=resolver-tests-version-1.grpctestingexp. \
+  --description="GCE-DNS-private-zone-for-GRPC-testing" \
+  --visibility=private \
+  --networks=default
diff --git a/test/cpp/naming/gen_build_yaml.py b/test/cpp/naming/gen_build_yaml.py
index 3a51fef7a0e..91718156e9a 100755
--- a/test/cpp/naming/gen_build_yaml.py
+++ b/test/cpp/naming/gen_build_yaml.py
@@ -24,6 +24,12 @@ import json
 
 _LOCAL_DNS_SERVER_ADDRESS = '127.0.0.1:15353'
 
+_TARGET_RECORDS_TO_SKIP_AGAINST_GCE = [
+  # TODO: enable this once able to upload the very large TXT record
+  # in this group to GCE DNS.
+  'ipv4-config-causing-fallback-to-tcp',
+]
+
 def _append_zone_name(name, zone_name):
   return '%s.%s' % (name, zone_name)
 
@@ -33,21 +39,107 @@ def _build_expected_addrs_cmd_arg(expected_addrs):
     out.append('%s,%s' % (addr['address'], str(addr['is_balancer'])))
   return ';'.join(out)
 
+def _data_for_type(r_type, r_data, common_zone_name):
+  if r_type in ['A', 'AAAA']:
+    return ' '.join(map(lambda x: '\"%s\"' % x, r_data))
+  if r_type == 'SRV':
+    assert len(r_data) == 1
+    target = r_data[0].split(' ')[3]
+    uploadable_target = '%s.%s' % (target, common_zone_name)
+    uploadable = r_data[0].split(' ')
+    uploadable[3] = uploadable_target
+    return '\"%s\"' % ' '.join(uploadable)
+  if r_type == 'TXT':
+    assert len(r_data) == 1
+    chunks = []
+    all_data = r_data[0]
+    cur = 0
+    # Split TXT records that span more than 255 characters (the single
+    # string length-limit in DNS) into multiple strings. Each string
+    # needs to be wrapped with double-quotes, and all inner double-quotes
+    # are escaped. The wrapping double-quotes and inner backslashes can be
+    # counted towards the 255 character length limit (as observed with gcloud),
+    # so make sure all strings fit within that limit.
+    while len(all_data[cur:]) > 0:
+      next_chunk = '\"'
+      while len(next_chunk) < 254 and len(all_data[cur:]) > 0:
+        if all_data[cur] == '\"':
+          if len(next_chunk) < 253:
+            next_chunk += '\\\"'
+          else:
+            break
+        else:
+          next_chunk += all_data[cur]
+        cur += 1
+      next_chunk += '\"'
+      if len(next_chunk) > 255:
+        raise Exception('Bug: next chunk is too long.')
+      chunks.append(next_chunk)
+    # Wrap the whole record in single quotes to make sure all strings
+    # are associated with the same TXT record (to make it one bash token for
+    # gcloud)
+    return '\'%s\'' % ' '.join(chunks)
+
+# Convert DNS records from their "within a test group" format
+# of the yaml file to an easier form for the templates to use.
+def _gcloud_uploadable_form(test_cases, common_zone_name):
+  out = []
+  for group in test_cases:
+    if group['record_to_resolve'] in _TARGET_RECORDS_TO_SKIP_AGAINST_GCE:
+      continue
+    for record_name in group['records'].keys():
+      r_ttl = None
+      all_r_data = {}
+      for r_data in group['records'][record_name]:
+        # enforce records have the same TTL only for simplicity
+        if r_ttl is None:
+          r_ttl = r_data['TTL']
+        assert r_ttl == r_data['TTL'], '%s and %s differ' % (r_ttl, r_data['TTL'])
+        r_type = r_data['type']
+        if all_r_data.get(r_type) is None:
+          all_r_data[r_type] = []
+        all_r_data[r_type].append(r_data['data'])
+      for r_type in all_r_data.keys():
+        for r in out:
+          assert r['name'] != record_name or r['type'] != r_type, 'attempt to add a duplicate record'
+        out.append({
+            'name': record_name,
+            'ttl': r_ttl,
+            'type': r_type,
+            'data': _data_for_type(r_type, all_r_data[r_type], common_zone_name)
+        })
+  return out
+
+def _gce_dns_zone_id(resolver_component_data):
+  dns_name = resolver_component_data['resolver_tests_common_zone_name']
+  return dns_name.replace('.', '-') + 'zone-id'
+
+def _resolver_test_cases(resolver_component_data, records_to_skip):
+  out = []
+  for test_case in resolver_component_data['resolver_component_tests']:
+    if test_case['record_to_resolve'] in records_to_skip:
+      continue
+    out.append({
+      'target_name': _append_zone_name(test_case['record_to_resolve'],
+                                       resolver_component_data['resolver_tests_common_zone_name']),
+      'expected_addrs': _build_expected_addrs_cmd_arg(test_case['expected_addrs']),
+      'expected_chosen_service_config': (test_case['expected_chosen_service_config'] or ''),
+      'expected_lb_policy': (test_case['expected_lb_policy'] or ''),
+    })
+  return out
+
 def main():
   resolver_component_data = ''
   with open('test/cpp/naming/resolver_test_record_groups.yaml') as f:
     resolver_component_data = yaml.load(f)
 
   json = {
-      'resolver_component_test_cases': [
-          {
-              'target_name': _append_zone_name(test_case['record_to_resolve'],
-                                                 resolver_component_data['resolver_component_tests_common_zone_name']),
-              'expected_addrs': _build_expected_addrs_cmd_arg(test_case['expected_addrs']),
-              'expected_chosen_service_config': (test_case['expected_chosen_service_config'] or ''),
-              'expected_lb_policy': (test_case['expected_lb_policy'] or ''),
-          } for test_case in resolver_component_data['resolver_component_tests']
-      ],
+      'resolver_tests_common_zone_name': resolver_component_data['resolver_tests_common_zone_name'],
+      'resolver_gce_integration_tests_zone_id': _gce_dns_zone_id(resolver_component_data),
+      'all_integration_test_records': _gcloud_uploadable_form(resolver_component_data['resolver_component_tests'],
+                                                              resolver_component_data['resolver_tests_common_zone_name']),
+      'resolver_gce_integration_test_cases': _resolver_test_cases(resolver_component_data, _TARGET_RECORDS_TO_SKIP_AGAINST_GCE),
+      'resolver_component_test_cases': _resolver_test_cases(resolver_component_data, []),
       'targets': [
           {
               'name': 'resolver_component_test' + unsecure_build_config_suffix,
diff --git a/test/cpp/naming/private_dns_zone_init.sh b/test/cpp/naming/private_dns_zone_init.sh
new file mode 100755
index 00000000000..4eaf750ab71
--- /dev/null
+++ b/test/cpp/naming/private_dns_zone_init.sh
@@ -0,0 +1,215 @@
+#!/bin/bash
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is auto-generated
+
+set -ex
+
+cd $(dirname $0)/../../..
+
+gcloud dns record-sets transaction start -z=resolver-tests-version-1-grpctestingexp-zone-id
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 ipv4-single-target.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-single-target.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 ipv4-multi-target.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-multi-target.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.5" "1.2.3.6" "1.2.3.7"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 ipv6-single-target.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv6-single-target.resolver-tests-version-1.grpctestingexp. \
+  --type=AAAA \
+  --ttl=2100 \
+  "2607:f8b0:400a:801::1001"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 ipv6-multi-target.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv6-multi-target.resolver-tests-version-1.grpctestingexp. \
+  --type=AAAA \
+  --ttl=2100 \
+  "2607:f8b0:400a:801::1002" "2607:f8b0:400a:801::1003" "2607:f8b0:400a:801::1004"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  --type=TXT \
+  --ttl=2100 \
+  '"grpc_config=[{\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"SimpleService\",\"waitForReady\":true}]}]}}]"'
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  --type=TXT \
+  --ttl=2100 \
+  '"grpc_config=[{\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"NoSrvSimpleService\",\"waitForReady\":true}]}]}}]"'
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. \
+  --type=TXT \
+  --ttl=2100 \
+  '"grpc_config=[{\"clientLanguage\":[\"python\"],\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"PythonService\",\"waitForReady\":true}]}]}}]"'
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. \
+  --type=TXT \
+  --ttl=2100 \
+  '"grpc_config=[{\"percentage\":0,\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"CppService\",\"waitForReady\":true}]}]}}]"'
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. \
+  --type=TXT \
+  --ttl=2100 \
+  '"grpc_config=[{\"clientLanguage\":[\"go\"],\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"GoService\",\"waitForReady\":true}]}]}},{\"clientLanguage\":[\"c++\"],\"serviceConfig\":{" "\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"CppService\",\"waitForReady\":true}]}]}}]"'
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. \
+  --type=TXT \
+  --ttl=2100 \
+  '"grpc_config=[{\"percentage\":0,\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"NeverPickedService\",\"waitForReady\":true}]}]}},{\"percentage\":100,\"serviceConfig\":{\"loadBalanc" "ingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"AlwaysPickedService\",\"waitForReady\":true}]}]}}]"'
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  --type=A \
+  --ttl=2100 \
+  "1.2.3.4"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  --type=SRV \
+  --ttl=2100 \
+  "0 0 1234 balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp."
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  --type=AAAA \
+  --ttl=2100 \
+  "2607:f8b0:400a:801::1002"
+
+gcloud dns record-sets transaction add \
+  -z=resolver-tests-version-1-grpctestingexp-zone-id \
+  --name=srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  --type=AAAA \
+  --ttl=2100 \
+  "2607:f8b0:400a:801::1002"
+
+gcloud dns record-sets transaction describe -z=resolver-tests-version-1-grpctestingexp-zone-id
+gcloud dns record-sets transaction execute -z=resolver-tests-version-1-grpctestingexp-zone-id
+gcloud dns record-sets list -z=resolver-tests-version-1-grpctestingexp-zone-id
diff --git a/test/cpp/naming/resolver_component_tests_runner.sh b/test/cpp/naming/resolver_component_tests_runner.sh
index cf71c9dcf97..407db5ed668 100755
--- a/test/cpp/naming/resolver_component_tests_runner.sh
+++ b/test/cpp/naming/resolver_component_tests_runner.sh
@@ -73,7 +73,7 @@ EXIT_CODE=0
 # in the resolver.
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-single-target.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -81,7 +81,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-multi-target.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.5:1234,True;1.2.3.6:1234,True;1.2.3.7:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -89,7 +89,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv6-single-target.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1001]:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -97,7 +97,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv6-multi-target.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1003]:1234,True;[2607:f8b0:400a:801::1004]:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -105,7 +105,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-simple-service-config.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -113,7 +113,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-no-srv-simple-service-config.resolver-tests.grpctestingexp.' \
+  --target_name='ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"NoSrvSimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -121,7 +121,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-no-config-for-cpp.resolver-tests.grpctestingexp.' \
+  --target_name='ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -129,7 +129,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests.grpctestingexp.' \
+  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -137,7 +137,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-second-language-is-cpp.resolver-tests.grpctestingexp.' \
+  --target_name='ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"CppService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -145,7 +145,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-config-with-percentages.resolver-tests.grpctestingexp.' \
+  --target_name='ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"AlwaysPickedService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -153,7 +153,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True;1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -161,7 +161,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests.grpctestingexp.' \
+  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1002]:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -169,7 +169,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-config-causing-fallback-to-tcp.resolver-tests.grpctestingexp.' \
+  --target_name='ipv4-config-causing-fallback-to-tcp.resolver-tests-version-1.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwo","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooThree","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooFour","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooFive","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooSix","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooSeven","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooEight","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooNine","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTen","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooEleven","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='' \
diff --git a/test/cpp/naming/resolver_gce_integration_tests_runner.sh b/test/cpp/naming/resolver_gce_integration_tests_runner.sh
new file mode 100755
index 00000000000..b20d18d9d10
--- /dev/null
+++ b/test/cpp/naming/resolver_gce_integration_tests_runner.sh
@@ -0,0 +1,359 @@
+#!/bin/bash
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is auto-generated
+
+set -ex
+
+if [[ "$GRPC_DNS_RESOLVER" == "" ]]; then
+  export GRPC_DNS_RESOLVER=ares
+elif [[ "$GRPC_DNS_RESOLVER" != ares ]]; then
+  echo "Unexpected: GRPC_DNS_RESOLVER=$GRPC_DNS_RESOLVER. This test only works with c-ares resolver"
+  exit 1
+fi
+
+cd $(dirname $0)/../../..
+
+if [[ "$CONFIG" == "" ]]; then
+  export CONFIG=opt
+fi
+make resolver_component_test
+echo "Sanity check DNS records are resolveable with dig:"
+EXIT_CODE=0
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig AAAA ipv6-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig AAAA ipv6-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig AAAA ipv6-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig AAAA ipv6-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig TXT srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig TXT srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig TXT ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig TXT ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig TXT ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig TXT ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig TXT ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig TXT ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig TXT ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig TXT ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig TXT ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig TXT ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig A srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig A srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig SRV _grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig AAAA balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig AAAA balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+ONE_FAILED=0
+dig AAAA srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Sanity check: dig AAAA srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  exit 1
+fi
+
+echo "Sanity check PASSED. Run resolver tests:"
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:1234,True' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.5:1234,True;1.2.3.6:1234,True;1.2.3.7:1234,True' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='[2607:f8b0:400a:801::1001]:1234,True' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1003]:1234,True;[2607:f8b0:400a:801::1004]:1234,True' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:1234,True' \
+  --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]}]}' \
+  --expected_lb_policy='round_robin' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:443,False' \
+  --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"NoSrvSimpleService","waitForReady":true}]}]}' \
+  --expected_lb_policy='round_robin' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:443,False' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:443,False' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:443,False' \
+  --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"CppService","waitForReady":true}]}]}' \
+  --expected_lb_policy='round_robin' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:443,False' \
+  --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"AlwaysPickedService","waitForReady":true}]}]}' \
+  --expected_lb_policy='round_robin' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='1.2.3.4:1234,True;1.2.3.4:443,False' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+ONE_FAILED=0
+bins/$CONFIG/resolver_component_test \
+  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
+  --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1002]:443,False' \
+  --expected_chosen_service_config='' \
+  --expected_lb_policy='' || ONE_FAILED=1
+if [[ "$ONE_FAILED" != 0 ]]; then
+  echo "Test based on target record: srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  EXIT_CODE=1
+fi
+
+exit $EXIT_CODE
diff --git a/test/cpp/naming/resolver_test_record_groups.yaml b/test/cpp/naming/resolver_test_record_groups.yaml
index 33d774ca701..2b3204335c4 100644
--- a/test/cpp/naming/resolver_test_record_groups.yaml
+++ b/test/cpp/naming/resolver_test_record_groups.yaml
@@ -1,4 +1,4 @@
-resolver_component_tests_common_zone_name: resolver-tests.grpctestingexp.
+resolver_tests_common_zone_name: resolver-tests-version-1.grpctestingexp.
 resolver_component_tests:
 - expected_addrs:
   - {address: '1.2.3.4:1234', is_balancer: true}
diff --git a/test/cpp/naming/test_dns_server.py b/test/cpp/naming/test_dns_server.py
index 9d4b89cffb5..9f42f65ee61 100755
--- a/test/cpp/naming/test_dns_server.py
+++ b/test/cpp/naming/test_dns_server.py
@@ -66,7 +66,7 @@ def start_local_dns_server(args):
 
   with open(args.records_config_path) as config:
     test_records_config = yaml.load(config)
-  common_zone_name = test_records_config['resolver_component_tests_common_zone_name']
+  common_zone_name = test_records_config['resolver_tests_common_zone_name']
   for group in test_records_config['resolver_component_tests']:
     for name in group['records'].keys():
       for record in group['records'][name]:
diff --git a/tools/codegen/core/gen_stats_data.py b/tools/codegen/core/gen_stats_data.py
index 10ad0cc831f..8359734c848 100755
--- a/tools/codegen/core/gen_stats_data.py
+++ b/tools/codegen/core/gen_stats_data.py
@@ -147,8 +147,7 @@ def gen_bucket_code(histogram):
     shift_data = find_ideal_shift(code_bounds[first_nontrivial:], 256 * histogram.buckets)
   #print first_nontrivial, shift_data, bounds
   #if shift_data is not None: print [hex(x >> shift_data[0]) for x in code_bounds[first_nontrivial:]]
-  code = '\n/* Automatically generated by tools/codegen/core/gen_stats_data.py */\n'
-  code += 'value = GPR_CLAMP(value, 0, %d);\n' % histogram.max
+  code = 'value = GPR_CLAMP(value, 0, %d);\n' % histogram.max
   map_table = gen_map_table(code_bounds[first_nontrivial:], shift_data)
   if first_nontrivial is None:
     code += ('GRPC_STATS_INC_HISTOGRAM((exec_ctx), GRPC_STATS_HISTOGRAM_%s, value);\n'
@@ -408,3 +407,4 @@ with open('src/core/lib/debug/stats_data_bq_schema.sql', 'w') as S:
   for counter in inst_map['Counter']:
     columns.append(('%s_per_iteration' % counter.name, 'FLOAT'))
   print >>S, ',\n'.join('%s:%s' % x for x in columns)
+
diff --git a/tools/github/pr_latency.py b/tools/github/pr_latency.py
new file mode 100644
index 00000000000..5d635835e54
--- /dev/null
+++ b/tools/github/pr_latency.py
@@ -0,0 +1,163 @@
+#!/usr/bin/env python
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Measure the time between PR creation and completion of all tests.
+
+You'll need a github API token to avoid being rate-limited. See
+https://help.github.com/articles/creating-a-personal-access-token-for-the-command-line/
+
+This script goes over the most recent 100 pull requests. For PRs with a single
+commit, it uses the PR's creation as the initial time; othewise, it uses the
+date of the last commit. This is somewhat fragile, and imposed by the fact that
+GitHub reports a PR's updated timestamp for any event that modifies the PR (e.g.
+comments), not just the addition of new commits.
+
+In addition, it ignores latencies greater than five hours, as that's likely due
+to a manual re-run of tests.
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import json
+import logging
+import pprint
+import urllib2
+
+from datetime import datetime, timedelta
+
+logging.basicConfig(format='%(asctime)s %(message)s')
+
+PRS = 'https://api.github.com/repos/grpc/grpc/pulls?state=open&per_page=100'
+COMMITS = 'https://api.github.com/repos/grpc/grpc/pulls/{pr_number}/commits'
+
+
+def gh(url):
+  request = urllib2.Request(url)
+  if TOKEN:
+    request.add_header('Authorization', 'token {}'.format(TOKEN))
+  response = urllib2.urlopen(request)
+  return response.read()
+
+
+def print_csv_header():
+  print('pr,base_time,test_time,latency_seconds,successes,failures,errors')
+
+
+def output(pr, base_time, test_time, diff_time, successes, failures, errors, mode='human'):
+  if mode == 'human':
+    print("PR #{} base time: {} UTC, Tests completed at: {} UTC. Latency: {}."
+          "\n\tSuccesses: {}, Failures: {}, Errors: {}".format(
+              pr, base_time, test_time, diff_time, successes, failures, errors))
+  elif mode == 'csv':
+    print(','.join([str(pr), str(base_time),
+                    str(test_time), str(int((test_time-base_time).total_seconds())),
+                    str(successes), str(failures), str(errors)]))
+
+
+def parse_timestamp(datetime_str):
+  return datetime.strptime(datetime_str, '%Y-%m-%dT%H:%M:%SZ')
+
+
+def to_posix_timestamp(dt):
+  return str((dt - datetime(1970, 1, 1)).total_seconds())
+
+
+def get_pr_data():
+  latest_prs = json.loads(gh(PRS))
+  res =  [{'number': pr['number'],
+           'created_at': parse_timestamp(pr['created_at']),
+           'updated_at': parse_timestamp(pr['updated_at']),
+           'statuses_url': pr['statuses_url']}
+          for pr in latest_prs]
+  return res
+
+
+def get_commits_data(pr_number):
+  commits = json.loads(gh(COMMITS.format(pr_number=pr_number)))
+  return {'num_commits': len(commits),
+          'most_recent_date': parse_timestamp(commits[-1]['commit']['author']['date'])}
+
+
+def get_status_data(statuses_url, system):
+  status_url = statuses_url.replace('statuses', 'status')
+  statuses = json.loads(gh(status_url + '?per_page=100'))
+  successes = 0
+  failures = 0
+  errors = 0
+  latest_datetime = None
+  if not statuses: return None
+  if system == 'kokoro': string_in_target_url = 'kokoro'
+  elif system == 'jenkins': string_in_target_url = 'grpc-testing'
+  for status in statuses['statuses']:
+    if not status['target_url'] or string_in_target_url not in status['target_url']: continue  # Ignore jenkins
+    if status['state'] == 'pending': return None
+    elif status['state'] == 'success': successes += 1
+    elif status['state'] == 'failure': failures += 1
+    elif status['state'] == 'error': errors += 1
+    if not latest_datetime:
+      latest_datetime = parse_timestamp(status['updated_at'])
+    else:
+      latest_datetime = max(latest_datetime, parse_timestamp(status['updated_at']))
+  # First status is the most recent one.
+  if any([successes, failures, errors]) and sum([successes, failures, errors]) > 15:
+    return {'latest_datetime': latest_datetime,
+            'successes': successes,
+            'failures': failures,
+            'errors': errors}
+  else: return None
+
+
+def build_args_parser():
+  import argparse
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--format', type=str, choices=['human', 'csv'],
+                      default='human',
+                      help='Output format: are you a human or a machine?')
+  parser.add_argument('--system', type=str, choices=['jenkins', 'kokoro'],
+                      required=True, help='Consider only the given CI system')
+  parser.add_argument('--token', type=str, default='',
+                      help='GitHub token to use its API with a higher rate limit')
+  return parser
+
+
+def main():
+  import sys
+  global TOKEN
+  args_parser = build_args_parser()
+  args = args_parser.parse_args()
+  TOKEN = args.token
+  if args.format == 'csv': print_csv_header()
+  for pr_data in get_pr_data():
+    commit_data = get_commits_data(pr_data['number'])
+    # PR with a single commit -> use the PRs creation time.
+    # else -> use the latest commit's date.
+    base_timestamp = pr_data['updated_at']
+    if commit_data['num_commits'] > 1:
+      base_timestamp = commit_data['most_recent_date']
+    else:
+      base_timestamp = pr_data['created_at']
+    last_status = get_status_data(pr_data['statuses_url'], args.system)
+    if last_status:
+      diff = last_status['latest_datetime'] - base_timestamp
+      if diff < timedelta(hours=5):
+        output(pr_data['number'], base_timestamp, last_status['latest_datetime'],
+               diff, last_status['successes'], last_status['failures'],
+               last_status['errors'], mode=args.format)
+
+
+if __name__ == '__main__':
+  main()
diff --git a/tools/internal_ci/linux/grpc_performance_profile_daily.sh b/tools/internal_ci/linux/grpc_performance_profile_daily.sh
index 25523e21b80..34d41bc04c6 100755
--- a/tools/internal_ci/linux/grpc_performance_profile_daily.sh
+++ b/tools/internal_ci/linux/grpc_performance_profile_daily.sh
@@ -22,6 +22,8 @@ source tools/internal_ci/helper_scripts/prepare_build_linux_perf_rc
 
 CPUS=`python -c 'import multiprocessing; print multiprocessing.cpu_count()'`
 
+./tools/run_tests/start_port_server.py || true
+
 make CONFIG=opt memory_profile_test memory_profile_client memory_profile_server -j $CPUS
 bins/opt/memory_profile_test
 bq load microbenchmarks.memory memory_usage.csv
diff --git a/tools/jenkins/run_performance_profile_daily.sh b/tools/jenkins/run_performance_profile_daily.sh
index 04a2464aee1..48d82a9b7f6 100755
--- a/tools/jenkins/run_performance_profile_daily.sh
+++ b/tools/jenkins/run_performance_profile_daily.sh
@@ -29,4 +29,6 @@ fi
 
 BENCHMARKS_TO_RUN="bm_fullstack_unary_ping_pong bm_fullstack_streaming_ping_pong bm_fullstack_streaming_pump bm_closure bm_cq bm_call_create bm_error bm_chttp2_hpack bm_chttp2_transport bm_pollset bm_metadata"
 
+./tools/run_tests/start_port_server.py || true
+
 $PYTHON tools/run_tests/run_microbenchmark.py --collect summary perf latency -b $BENCHMARKS_TO_RUN
diff --git a/tools/run_tests/performance/massage_qps_stats.py b/tools/run_tests/performance/massage_qps_stats.py
index e1620adad26..9b9355308a3 100644
--- a/tools/run_tests/performance/massage_qps_stats.py
+++ b/tools/run_tests/performance/massage_qps_stats.py
@@ -106,8 +106,6 @@ def massage_qps_stats(scenario_result):
     stats["core_executor_wakeup_initiated"] = massage_qps_stats_helpers.counter(core_stats, "executor_wakeup_initiated")
     stats["core_executor_queue_drained"] = massage_qps_stats_helpers.counter(core_stats, "executor_queue_drained")
     stats["core_executor_push_retries"] = massage_qps_stats_helpers.counter(core_stats, "executor_push_retries")
-    stats["core_executor_threads_created"] = massage_qps_stats_helpers.counter(core_stats, "executor_threads_created")
-    stats["core_executor_threads_used"] = massage_qps_stats_helpers.counter(core_stats, "executor_threads_used")
     stats["core_server_requested_calls"] = massage_qps_stats_helpers.counter(core_stats, "server_requested_calls")
     stats["core_server_slowpath_requests_queued"] = massage_qps_stats_helpers.counter(core_stats, "server_slowpath_requests_queued")
     h = massage_qps_stats_helpers.histogram(core_stats, "call_initial_size")
@@ -182,12 +180,6 @@ def massage_qps_stats(scenario_result):
     stats["core_http2_send_flowctl_per_write_50p"] = massage_qps_stats_helpers.percentile(h.buckets, 50, h.boundaries)
     stats["core_http2_send_flowctl_per_write_95p"] = massage_qps_stats_helpers.percentile(h.buckets, 95, h.boundaries)
     stats["core_http2_send_flowctl_per_write_99p"] = massage_qps_stats_helpers.percentile(h.buckets, 99, h.boundaries)
-    h = massage_qps_stats_helpers.histogram(core_stats, "executor_closures_per_wakeup")
-    stats["core_executor_closures_per_wakeup"] = ",".join("%f" % x for x in h.buckets)
-    stats["core_executor_closures_per_wakeup_bkts"] = ",".join("%f" % x for x in h.boundaries)
-    stats["core_executor_closures_per_wakeup_50p"] = massage_qps_stats_helpers.percentile(h.buckets, 50, h.boundaries)
-    stats["core_executor_closures_per_wakeup_95p"] = massage_qps_stats_helpers.percentile(h.buckets, 95, h.boundaries)
-    stats["core_executor_closures_per_wakeup_99p"] = massage_qps_stats_helpers.percentile(h.buckets, 99, h.boundaries)
     h = massage_qps_stats_helpers.histogram(core_stats, "server_cqs_checked")
     stats["core_server_cqs_checked"] = ",".join("%f" % x for x in h.buckets)
     stats["core_server_cqs_checked_bkts"] = ",".join("%f" % x for x in h.boundaries)
diff --git a/tools/run_tests/performance/scenario_result_schema.json b/tools/run_tests/performance/scenario_result_schema.json
index c7b1904bd19..2f0fd916d4f 100644
--- a/tools/run_tests/performance/scenario_result_schema.json
+++ b/tools/run_tests/performance/scenario_result_schema.json
@@ -540,16 +540,6 @@
         "name": "core_executor_push_retries", 
         "type": "INTEGER"
       }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_threads_created", 
-        "type": "INTEGER"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_threads_used", 
-        "type": "INTEGER"
-      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_server_requested_calls", 
@@ -860,31 +850,6 @@
         "name": "core_http2_send_flowctl_per_write_99p", 
         "type": "FLOAT"
       }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup", 
-        "type": "STRING"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_bkts", 
-        "type": "STRING"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_50p", 
-        "type": "FLOAT"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_95p", 
-        "type": "FLOAT"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_99p", 
-        "type": "FLOAT"
-      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_server_cqs_checked", 
@@ -1367,16 +1332,6 @@
         "name": "core_executor_push_retries", 
         "type": "INTEGER"
       }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_threads_created", 
-        "type": "INTEGER"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_threads_used", 
-        "type": "INTEGER"
-      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_server_requested_calls", 
@@ -1687,31 +1642,6 @@
         "name": "core_http2_send_flowctl_per_write_99p", 
         "type": "FLOAT"
       }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup", 
-        "type": "STRING"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_bkts", 
-        "type": "STRING"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_50p", 
-        "type": "FLOAT"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_95p", 
-        "type": "FLOAT"
-      }, 
-      {
-        "mode": "NULLABLE", 
-        "name": "core_executor_closures_per_wakeup_99p", 
-        "type": "FLOAT"
-      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_server_cqs_checked", 
diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index b38108d456c..6697149dd9c 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -717,6 +717,9 @@ class PythonLanguage(object):
       return (pypy32_config,)
     elif args.compiler == 'python_alpine':
       return (python27_config,)
+    elif args.compiler == 'all_the_cpythons':
+      return (python27_config, python34_config, python35_config,
+              python36_config,)
     else:
       raise Exception('Compiler %s not supported.' % args.compiler)
 
@@ -1214,7 +1217,7 @@ argp.add_argument('--compiler',
                   choices=['default',
                            'gcc4.4', 'gcc4.6', 'gcc4.8', 'gcc4.9', 'gcc5.3', 'gcc_musl',
                            'clang3.4', 'clang3.5', 'clang3.6', 'clang3.7',
-                           'python2.7', 'python3.4', 'python3.5', 'python3.6', 'pypy', 'pypy3', 'python_alpine',
+                           'python2.7', 'python3.4', 'python3.5', 'python3.6', 'pypy', 'pypy3', 'python_alpine', 'all_the_cpythons',
                            'node0.12', 'node4', 'node5', 'node6', 'node7', 'node8',
                            'electron1.3', 'electron1.6',
                            'coreclr',