diff --git a/BUILD b/BUILD
index 67c14ca32ea..5153bf66847 100644
--- a/BUILD
+++ b/BUILD
@@ -1319,3 +1319,21 @@ objc_bundle_library(
     name = "gRPCCertificates",
     resources = ["etc/roots.pem"],
 )
+
+proto_objc_rpc_path = objc_path + "/ProtoRPC"
+
+objc_library(
+  name = "proto_objc_rpc",
+  hdrs = glob([
+    proto_objc_rpc_path + "/*.h",
+  ]),
+  srcs = glob([
+    proto_objc_rpc_path + "/*.m",
+  ]),
+  includes = [objc_path],
+  deps = [
+    ":grpc_client",
+    ":rx_library",
+    "//external:protobuf_objc",
+  ],
+)
diff --git a/Makefile b/Makefile
index 1038158524e..9523e95052b 100644
--- a/Makefile
+++ b/Makefile
@@ -331,6 +331,8 @@ HOST_LDLIBS = $(LDLIBS)
 # These are automatically computed variables.
 # There shouldn't be any need to change anything from now on.
 
+HAS_PKG_CONFIG = $(shell command -v pkg-config >/dev/null 2>&1 && echo true || echo false)
+
 ifeq ($(SYSTEM),MINGW32)
 SHARED_EXT = dll
 endif
@@ -355,6 +357,13 @@ ifeq ($(SYSTEM),Darwin)
 OPENSSL_REQUIRES_DL = true
 endif
 
+ifeq ($(HAS_PKG_CONFIG),true)
+OPENSSL_ALPN_CHECK_CMD = pkg-config --atleast-version=1.0.2 openssl
+ZLIB_CHECK_CMD = pkg-config --exists zlib
+PERFTOOLS_CHECK_CMD = pkg-config --exists profiler
+PROTOBUF_CHECK_CMD = pkg-config --atleast-version=3.0.0-alpha-3 protobuf
+else # HAS_PKG_CONFIG
+
 ifeq ($(SYSTEM),MINGW32)
 OPENSSL_LIBS = ssl32 eay32
 else
@@ -365,15 +374,18 @@ OPENSSL_ALPN_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/ope
 ZLIB_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/zlib.c -lz $(LDFLAGS)
 PERFTOOLS_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/perftools.c -lprofiler $(LDFLAGS)
 PROTOBUF_CHECK_CMD = $(CXX) $(CXXFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/protobuf.cc -lprotobuf $(LDFLAGS)
-PROTOC_CHECK_CMD = which protoc > /dev/null
-PROTOC_CHECK_VERSION_CMD = protoc --version | grep -q libprotoc.3
-DTRACE_CHECK_CMD = which dtrace > /dev/null
-SYSTEMTAP_HEADERS_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/systemtap.c $(LDFLAGS)
 
 ifeq ($(OPENSSL_REQUIRES_DL),true)
 OPENSSL_ALPN_CHECK_CMD += -ldl
 endif
 
+endif # HAS_PKG_CONFIG
+
+PROTOC_CHECK_CMD = which protoc > /dev/null
+PROTOC_CHECK_VERSION_CMD = protoc --version | grep -q libprotoc.3
+DTRACE_CHECK_CMD = which dtrace > /dev/null
+SYSTEMTAP_HEADERS_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/systemtap.c $(LDFLAGS)
+
 ifndef REQUIRE_CUSTOM_LIBRARIES_$(CONFIG)
 HAS_SYSTEM_PERFTOOLS = $(shell $(PERFTOOLS_CHECK_CMD) 2> /dev/null && echo true || echo false)
 ifeq ($(HAS_SYSTEM_PERFTOOLS),true)
@@ -442,9 +454,33 @@ LDFLAGS += -L$(LIBDIR)/$(CONFIG)/zlib
 else
 DEP_MISSING += zlib
 endif
+else
+ifeq ($(HAS_PKG_CONFIG),true)
+CPPFLAGS += $(shell pkg-config --cflags zlib)
+LDFLAGS += $(shell pkg-config --libs-only-L zlib)
+endif
 endif
 
-ifeq ($(HAS_SYSTEM_OPENSSL_ALPN),false)
+OPENSSL_PKG_CONFIG = false
+
+ifeq ($(HAS_SYSTEM_OPENSSL_ALPN),true)
+ifeq ($(HAS_PKG_CONFIG),true)
+OPENSSL_PKG_CONFIG = true
+CPPFLAGS := $(shell pkg-config --cflags openssl) $(CPPFLAGS)
+LDFLAGS_OPENSSL_PKG_CONFIG = $(shell pkg-config --libs-only-L openssl)
+ifeq ($(SYSTEM),Linux)
+ifneq ($(LDFLAGS_OPENSSL_PKG_CONFIG),)
+LDFLAGS_OPENSSL_PKG_CONFIG += $(shell pkg-config --libs-only-L openssl | sed s/L/Wl,-rpath,/)
+endif
+endif
+LDFLAGS := $(LDFLAGS_OPENSSL_PKG_CONFIG) $(LDFLAGS)
+else
+LIBS_SECURE = $(OPENSSL_LIBS)
+ifeq ($(OPENSSL_REQUIRES_DL),true)
+LIBS_SECURE += dl
+endif
+endif
+else
 ifeq ($(HAS_EMBEDDED_OPENSSL_ALPN),true)
 OPENSSL_DEP = $(LIBDIR)/$(CONFIG)/openssl/libssl.a
 OPENSSL_MERGE_LIBS += $(LIBDIR)/$(CONFIG)/openssl/libssl.a $(LIBDIR)/$(CONFIG)/openssl/libcrypto.a
@@ -457,16 +493,28 @@ endif
 else
 NO_SECURE = true
 endif
-else
-LIBS_SECURE = $(OPENSSL_LIBS)
-ifeq ($(OPENSSL_REQUIRES_DL),true)
-LIBS_SECURE += dl
-endif
 endif
 
+ifeq ($(OPENSSL_PKG_CONFIG),true)
+LDLIBS_SECURE += $(shell pkg-config --libs-only-l openssl)
+else
 LDLIBS_SECURE += $(addprefix -l, $(LIBS_SECURE))
+endif
+
+PROTOBUF_PKG_CONFIG = false
 
-ifeq ($(HAS_SYSTEM_PROTOBUF),false)
+ifeq ($(HAS_SYSTEM_PROTOBUF),true)
+ifeq ($(HAS_PKG_CONFIG),true)
+PROTOBUF_PKG_CONFIG = true
+CPPFLAGS := $(shell pkg-config --cflags protobuf) $(CPPFLAGS)
+LDFLAGS_PROTOBUF_PKG_CONFIG = $(shell pkg-config --libs-only-L protobuf)
+ifeq ($(SYSTEM),Linux)
+ifneq ($(LDFLAGS_PROTOBUF_PKG_CONFIG),)
+LDFLAGS_PROTOBUF_PKG_CONFIG += $(shell pkg-config --libs-only-L protobuf | sed s/L/Wl,-rpath,/)
+endif
+endif
+endif
+else
 ifeq ($(HAS_EMBEDDED_PROTOBUF),true)
 PROTOBUF_DEP = $(LIBDIR)/$(CONFIG)/protobuf/libprotobuf.a
 CPPFLAGS := -Ithird_party/protobuf/src $(CPPFLAGS)
@@ -475,15 +523,19 @@ PROTOC = $(BINDIR)/$(CONFIG)/protobuf/protoc
 else
 NO_PROTOBUF = true
 endif
-else
 endif
 
 LIBS_PROTOBUF = protobuf
 LIBS_PROTOC = protoc protobuf
 
-LDLIBS_PROTOBUF += $(addprefix -l, $(LIBS_PROTOBUF))
 HOST_LDLIBS_PROTOC += $(addprefix -l, $(LIBS_PROTOC))
 
+ifeq ($(PROTOBUF_PKG_CONFIG),true)
+LDLIBS_PROTOBUF += $(shell pkg-config --libs-only-l protobuf)
+else
+LDLIBS_PROTOBUF += $(addprefix -l, $(LIBS_PROTOBUF))
+endif
+
 ifeq ($(MAKECMDGOALS),clean)
 NO_DEPS = true
 endif
diff --git a/src/objective-c/ProtoRPC/ProtoRPC.m b/src/objective-c/ProtoRPC/ProtoRPC.m
index 39120344156..4da646d7b45 100644
--- a/src/objective-c/ProtoRPC/ProtoRPC.m
+++ b/src/objective-c/ProtoRPC/ProtoRPC.m
@@ -33,7 +33,7 @@
 
 #import "ProtoRPC.h"
 
-#import <Protobuf/GPBProtocolBuffers.h>
+#import <GPBProtocolBuffers.h>
 #import <RxLibrary/GRXWriteable.h>
 #import <RxLibrary/GRXWriter.h>
 #import <RxLibrary/GRXWriter+Transformations.h>
@@ -66,6 +66,8 @@
   // A writer that serializes the proto messages to send.
   id<GRXWriter> bytesWriter =
       [[[GRXWriter alloc] initWithWriter:requestsWriter] map:^id(GPBMessage *proto) {
+        // TODO(jcanizales): Fail with an understandable error message if the requestsWriter isn't
+        // sending GPBMessages.
         return [proto data];
       }];
   if ((self = [super initWithHost:host method:method requestsWriter:bytesWriter])) {
diff --git a/src/php/bin/determine_extension_dir.sh b/src/php/bin/determine_extension_dir.sh
index 6fc392afc0a..6bbd934bf13 100755
--- a/src/php/bin/determine_extension_dir.sh
+++ b/src/php/bin/determine_extension_dir.sh
@@ -29,15 +29,15 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 set -e
-default_extension_dir=$(php -i | grep extension_dir | sed 's/.*=> //g')
+default_extension_dir=$(php-config --extension-dir)
 if command -v brew >/dev/null && [ -d $(brew --prefix)/opt/grpc-php ]; then
   # homebrew and the grpc-php formula are installed
   extension_dir="-d extension_dir="$(brew --prefix)/opt/grpc-php
-elif [ ! -f $default_extension_dir/grpc.so ]; then
+elif [ ! -e $default_extension_dir/grpc.so ]; then
   # the grpc extension is not found in the default PHP extension dir
   # try the source modules directory
   module_dir=../ext/grpc/modules
-  if [ ! -f $module_dir/grpc.so ]; then
+  if [ ! -e $module_dir/grpc.so ]; then
     echo "Please run 'phpize && ./configure && make' from ext/grpc first"
     exit 1
   fi
diff --git a/src/python/src/grpc/_adapter/_c/types.h b/src/python/src/grpc/_adapter/_c/types.h
index e189ae25660..3449f0643f7 100644
--- a/src/python/src/grpc/_adapter/_c/types.h
+++ b/src/python/src/grpc/_adapter/_c/types.h
@@ -241,10 +241,10 @@ double pygrpc_cast_gpr_timespec_to_double(gpr_timespec timespec);
 gpr_timespec pygrpc_cast_double_to_gpr_timespec(double seconds);
 
 /* Returns true on success, false on failure. */
-int pygrpc_cast_pylist_to_send_metadata(
-    PyObject *pylist, grpc_metadata **metadata, size_t *count);
+int pygrpc_cast_pyseq_to_send_metadata(
+    PyObject *pyseq, grpc_metadata **metadata, size_t *count);
 /* Returns a metadata array as a Python object on success, else NULL. */
-PyObject *pygrpc_cast_metadata_array_to_pylist(grpc_metadata_array metadata);
+PyObject *pygrpc_cast_metadata_array_to_pyseq(grpc_metadata_array metadata);
 
 /* Transliterate from a list of python channel arguments (2-tuples of string
    and string|integer|None) to a grpc_channel_args object. The strings placed
diff --git a/src/python/src/grpc/_adapter/_c/utility.c b/src/python/src/grpc/_adapter/_c/utility.c
index a433f26d769..480a720c21f 100644
--- a/src/python/src/grpc/_adapter/_c/utility.c
+++ b/src/python/src/grpc/_adapter/_c/utility.c
@@ -32,6 +32,7 @@
  */
 
 #include <math.h>
+#include <string.h>
 
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
@@ -118,7 +119,7 @@ PyObject *pygrpc_consume_event(grpc_event event) {
           tag->request_call_details.method, tag->request_call_details.host,
           pygrpc_cast_gpr_timespec_to_double(tag->request_call_details.deadline),
           GRPC_OP_RECV_INITIAL_METADATA,
-          pygrpc_cast_metadata_array_to_pylist(tag->request_metadata), Py_None,
+          pygrpc_cast_metadata_array_to_pyseq(tag->request_metadata), Py_None,
           Py_None, Py_None, Py_None,
           event.success ? Py_True : Py_False);
     } else {
@@ -172,7 +173,7 @@ int pygrpc_produce_op(PyObject *op, grpc_op *result) {
   c_op.flags = 0;
   switch (type) {
   case GRPC_OP_SEND_INITIAL_METADATA:
-    if (!pygrpc_cast_pylist_to_send_metadata(
+    if (!pygrpc_cast_pyseq_to_send_metadata(
             PyTuple_GetItem(op, INITIAL_METADATA_INDEX),
             &c_op.data.send_initial_metadata.metadata,
             &c_op.data.send_initial_metadata.count)) {
@@ -190,7 +191,7 @@ int pygrpc_produce_op(PyObject *op, grpc_op *result) {
     /* Don't need to fill in any other fields. */
     break;
   case GRPC_OP_SEND_STATUS_FROM_SERVER:
-    if (!pygrpc_cast_pylist_to_send_metadata(
+    if (!pygrpc_cast_pyseq_to_send_metadata(
             PyTuple_GetItem(op, TRAILING_METADATA_INDEX),
             &c_op.data.send_status_from_server.trailing_metadata,
             &c_op.data.send_status_from_server.trailing_metadata_count)) {
@@ -247,8 +248,16 @@ int pygrpc_produce_op(PyObject *op, grpc_op *result) {
 }
 
 void pygrpc_discard_op(grpc_op op) {
+  size_t i;
   switch(op.op) {
   case GRPC_OP_SEND_INITIAL_METADATA:
+    /* Whenever we produce send-metadata, we allocate new strings (to handle
+       arbitrary sequence input as opposed to just lists or just tuples). We
+       thus must free those elements. */
+    for (i = 0; i < op.data.send_initial_metadata.count; ++i) {
+      gpr_free((void *)op.data.send_initial_metadata.metadata[i].key);
+      gpr_free((void *)op.data.send_initial_metadata.metadata[i].value);
+    }
     gpr_free(op.data.send_initial_metadata.metadata);
     break;
   case GRPC_OP_SEND_MESSAGE:
@@ -258,6 +267,16 @@ void pygrpc_discard_op(grpc_op op) {
     /* Don't need to free any fields. */
     break;
   case GRPC_OP_SEND_STATUS_FROM_SERVER:
+    /* Whenever we produce send-metadata, we allocate new strings (to handle
+       arbitrary sequence input as opposed to just lists or just tuples). We
+       thus must free those elements. */
+    for (i = 0; i < op.data.send_status_from_server.trailing_metadata_count;
+         ++i) {
+      gpr_free(
+          (void *)op.data.send_status_from_server.trailing_metadata[i].key);
+      gpr_free(
+          (void *)op.data.send_status_from_server.trailing_metadata[i].value);
+    }
     gpr_free(op.data.send_status_from_server.trailing_metadata);
     gpr_free((char *)op.data.send_status_from_server.status_details);
     break;
@@ -419,31 +438,41 @@ void pygrpc_discard_channel_args(grpc_channel_args args) {
   gpr_free(args.args);
 }
 
-int pygrpc_cast_pylist_to_send_metadata(
-    PyObject *pylist, grpc_metadata **metadata, size_t *count) {
+int pygrpc_cast_pyseq_to_send_metadata(
+    PyObject *pyseq, grpc_metadata **metadata, size_t *count) {
   size_t i;
   Py_ssize_t value_length;
-  *count = PyList_Size(pylist);
+  char *key;
+  char *value;
+  if (!PySequence_Check(pyseq)) {
+    return 0;
+  }
+  *count = PySequence_Size(pyseq);
   *metadata = gpr_malloc(sizeof(grpc_metadata) * *count);
   for (i = 0; i < *count; ++i) {
-    if (!PyArg_ParseTuple(
-        PyList_GetItem(pylist, i), "ss#",
-        &(*metadata)[i].key, &(*metadata)[i].value, &value_length)) {
+    PyObject *item = PySequence_GetItem(pyseq, i);
+    if (!PyArg_ParseTuple(item, "ss#", &key, &value, &value_length)) {
+      Py_DECREF(item);
       gpr_free(*metadata);
       *count = 0;
       *metadata = NULL;
       return 0;
+    } else {
+      (*metadata)[i].key = gpr_strdup(key);
+      (*metadata)[i].value = gpr_malloc(value_length);
+      memcpy((void *)(*metadata)[i].value, value, value_length);
+      Py_DECREF(item);
     }
     (*metadata)[i].value_length = value_length;
   }
   return 1;
 }
 
-PyObject *pygrpc_cast_metadata_array_to_pylist(grpc_metadata_array metadata) {
-  PyObject *result = PyList_New(metadata.count);
+PyObject *pygrpc_cast_metadata_array_to_pyseq(grpc_metadata_array metadata) {
+  PyObject *result = PyTuple_New(metadata.count);
   size_t i;
   for (i = 0; i < metadata.count; ++i) {
-    PyList_SetItem(
+    PyTuple_SetItem(
         result, i, Py_BuildValue(
             "ss#", metadata.metadata[i].key, metadata.metadata[i].value,
             (Py_ssize_t)metadata.metadata[i].value_length));
diff --git a/src/python/src/grpc/_adapter/_intermediary_low.py b/src/python/src/grpc/_adapter/_intermediary_low.py
index 6b96aef1d34..3c7f0a26197 100644
--- a/src/python/src/grpc/_adapter/_intermediary_low.py
+++ b/src/python/src/grpc/_adapter/_intermediary_low.py
@@ -144,10 +144,11 @@ class Call(object):
     self._metadata.append((key, value))
 
   def premetadata(self):
-    return self._internal.start_batch([
+    result = self._internal.start_batch([
           _types.OpArgs.send_initial_metadata(self._metadata)
       ], _IGNORE_ME_TAG)
     self._metadata = []
+    return result
 
   def read(self, tag):
     return self._internal.start_batch([
diff --git a/src/python/src/grpc/_adapter/_intermediary_low_test.py b/src/python/src/grpc/_adapter/_intermediary_low_test.py
index 1a9b0c69f3c..27a5b82e9c4 100644
--- a/src/python/src/grpc/_adapter/_intermediary_low_test.py
+++ b/src/python/src/grpc/_adapter/_intermediary_low_test.py
@@ -282,6 +282,9 @@ class EchoTest(unittest.TestCase):
     self.assertIn(server_trailing_binary_metadata_key, metadata)
     self.assertEqual(server_trailing_binary_metadata_value,
                      metadata[server_trailing_binary_metadata_key])
+    self.assertSetEqual(set(key for key, _ in finish_accepted.metadata),
+                        set((server_trailing_metadata_key,
+                             server_trailing_binary_metadata_key,)))
 
     server_timeout_none_event = self.server_completion_queue.get(0)
     self.assertIsNone(server_timeout_none_event)
diff --git a/templates/BUILD.template b/templates/BUILD.template
index 4d2bf7db283..dffdc1dddde 100644
--- a/templates/BUILD.template
+++ b/templates/BUILD.template
@@ -205,3 +205,21 @@ objc_bundle_library(
     name = "gRPCCertificates",
     resources = ["etc/roots.pem"],
 )
+
+proto_objc_rpc_path = objc_path + "/ProtoRPC"
+
+objc_library(
+  name = "proto_objc_rpc",
+  hdrs = glob([
+    proto_objc_rpc_path + "/*.h",
+  ]),
+  srcs = glob([
+    proto_objc_rpc_path + "/*.m",
+  ]),
+  includes = [objc_path],
+  deps = [
+    ":grpc_client",
+    ":rx_library",
+    "//external:protobuf_objc",
+  ],
+)
diff --git a/templates/Makefile.template b/templates/Makefile.template
index ebe207f1918..3b04d7d0415 100644
--- a/templates/Makefile.template
+++ b/templates/Makefile.template
@@ -345,6 +345,8 @@ HOST_LDLIBS = $(LDLIBS)
 # These are automatically computed variables.
 # There shouldn't be any need to change anything from now on.
 
+HAS_PKG_CONFIG = $(shell command -v pkg-config >/dev/null 2>&1 && echo true || echo false)
+
 ifeq ($(SYSTEM),MINGW32)
 SHARED_EXT = dll
 endif
@@ -369,6 +371,13 @@ ifeq ($(SYSTEM),Darwin)
 OPENSSL_REQUIRES_DL = true
 endif
 
+ifeq ($(HAS_PKG_CONFIG),true)
+OPENSSL_ALPN_CHECK_CMD = pkg-config --atleast-version=1.0.2 openssl
+ZLIB_CHECK_CMD = pkg-config --exists zlib
+PERFTOOLS_CHECK_CMD = pkg-config --exists profiler
+PROTOBUF_CHECK_CMD = pkg-config --atleast-version=3.0.0-alpha-3 protobuf
+else # HAS_PKG_CONFIG
+
 ifeq ($(SYSTEM),MINGW32)
 OPENSSL_LIBS = ssl32 eay32
 else
@@ -379,15 +388,18 @@ OPENSSL_ALPN_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/ope
 ZLIB_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/zlib.c -lz $(LDFLAGS)
 PERFTOOLS_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/perftools.c -lprofiler $(LDFLAGS)
 PROTOBUF_CHECK_CMD = $(CXX) $(CXXFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/protobuf.cc -lprotobuf $(LDFLAGS)
-PROTOC_CHECK_CMD = which protoc > /dev/null
-PROTOC_CHECK_VERSION_CMD = protoc --version | grep -q libprotoc.3
-DTRACE_CHECK_CMD = which dtrace > /dev/null
-SYSTEMTAP_HEADERS_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/systemtap.c $(LDFLAGS)
 
 ifeq ($(OPENSSL_REQUIRES_DL),true)
 OPENSSL_ALPN_CHECK_CMD += -ldl
 endif
 
+endif # HAS_PKG_CONFIG
+
+PROTOC_CHECK_CMD = which protoc > /dev/null
+PROTOC_CHECK_VERSION_CMD = protoc --version | grep -q libprotoc.3
+DTRACE_CHECK_CMD = which dtrace > /dev/null
+SYSTEMTAP_HEADERS_CHECK_CMD = $(CC) $(CFLAGS) $(CPPFLAGS) -o $(TMPOUT) test/build/systemtap.c $(LDFLAGS)
+
 ifndef REQUIRE_CUSTOM_LIBRARIES_$(CONFIG)
 HAS_SYSTEM_PERFTOOLS = $(shell $(PERFTOOLS_CHECK_CMD) 2> /dev/null && echo true || echo false)
 ifeq ($(HAS_SYSTEM_PERFTOOLS),true)
@@ -456,9 +468,33 @@ LDFLAGS += -L$(LIBDIR)/$(CONFIG)/zlib
 else
 DEP_MISSING += zlib
 endif
+else
+ifeq ($(HAS_PKG_CONFIG),true)
+CPPFLAGS += $(shell pkg-config --cflags zlib)
+LDFLAGS += $(shell pkg-config --libs-only-L zlib)
+endif
 endif
 
-ifeq ($(HAS_SYSTEM_OPENSSL_ALPN),false)
+OPENSSL_PKG_CONFIG = false
+
+ifeq ($(HAS_SYSTEM_OPENSSL_ALPN),true)
+ifeq ($(HAS_PKG_CONFIG),true)
+OPENSSL_PKG_CONFIG = true
+CPPFLAGS := $(shell pkg-config --cflags openssl) $(CPPFLAGS)
+LDFLAGS_OPENSSL_PKG_CONFIG = $(shell pkg-config --libs-only-L openssl)
+ifeq ($(SYSTEM),Linux)
+ifneq ($(LDFLAGS_OPENSSL_PKG_CONFIG),)
+LDFLAGS_OPENSSL_PKG_CONFIG += $(shell pkg-config --libs-only-L openssl | sed s/L/Wl,-rpath,/)
+endif
+endif
+LDFLAGS := $(LDFLAGS_OPENSSL_PKG_CONFIG) $(LDFLAGS)
+else
+LIBS_SECURE = $(OPENSSL_LIBS)
+ifeq ($(OPENSSL_REQUIRES_DL),true)
+LIBS_SECURE += dl
+endif
+endif
+else
 ifeq ($(HAS_EMBEDDED_OPENSSL_ALPN),true)
 OPENSSL_DEP = $(LIBDIR)/$(CONFIG)/openssl/libssl.a
 OPENSSL_MERGE_LIBS += $(LIBDIR)/$(CONFIG)/openssl/libssl.a $(LIBDIR)/$(CONFIG)/openssl/libcrypto.a
@@ -471,16 +507,28 @@ endif
 else
 NO_SECURE = true
 endif
-else
-LIBS_SECURE = $(OPENSSL_LIBS)
-ifeq ($(OPENSSL_REQUIRES_DL),true)
-LIBS_SECURE += dl
-endif
 endif
 
+ifeq ($(OPENSSL_PKG_CONFIG),true)
+LDLIBS_SECURE += $(shell pkg-config --libs-only-l openssl)
+else
 LDLIBS_SECURE += $(addprefix -l, $(LIBS_SECURE))
+endif
+
+PROTOBUF_PKG_CONFIG = false
 
-ifeq ($(HAS_SYSTEM_PROTOBUF),false)
+ifeq ($(HAS_SYSTEM_PROTOBUF),true)
+ifeq ($(HAS_PKG_CONFIG),true)
+PROTOBUF_PKG_CONFIG = true
+CPPFLAGS := $(shell pkg-config --cflags protobuf) $(CPPFLAGS)
+LDFLAGS_PROTOBUF_PKG_CONFIG = $(shell pkg-config --libs-only-L protobuf)
+ifeq ($(SYSTEM),Linux)
+ifneq ($(LDFLAGS_PROTOBUF_PKG_CONFIG),)
+LDFLAGS_PROTOBUF_PKG_CONFIG += $(shell pkg-config --libs-only-L protobuf | sed s/L/Wl,-rpath,/)
+endif
+endif
+endif
+else
 ifeq ($(HAS_EMBEDDED_PROTOBUF),true)
 PROTOBUF_DEP = $(LIBDIR)/$(CONFIG)/protobuf/libprotobuf.a
 CPPFLAGS := -Ithird_party/protobuf/src $(CPPFLAGS)
@@ -489,15 +537,19 @@ PROTOC = $(BINDIR)/$(CONFIG)/protobuf/protoc
 else
 NO_PROTOBUF = true
 endif
-else
 endif
 
 LIBS_PROTOBUF = protobuf
 LIBS_PROTOC = protoc protobuf
 
-LDLIBS_PROTOBUF += $(addprefix -l, $(LIBS_PROTOBUF))
 HOST_LDLIBS_PROTOC += $(addprefix -l, $(LIBS_PROTOC))
 
+ifeq ($(PROTOBUF_PKG_CONFIG),true)
+LDLIBS_PROTOBUF += $(shell pkg-config --libs-only-l protobuf)
+else
+LDLIBS_PROTOBUF += $(addprefix -l, $(LIBS_PROTOBUF))
+endif
+
 ifeq ($(MAKECMDGOALS),clean)
 NO_DEPS = true
 endif