diff --git a/BUILD b/BUILD
index 1158e48d0e..296bda23f2 100644
--- a/BUILD
+++ b/BUILD
@@ -109,6 +109,16 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "mini_table_internal",
+    hdrs = ["upb/msg_internal.h"],
+    deps = [
+        ":port",
+        ":table",
+        ":upb",
+    ],
+)
+
 cc_library(
     name = "mini_table",
     srcs = ["upb/mini_table.c"],
@@ -118,7 +128,11 @@ cc_library(
     ],
     copts = UPB_DEFAULT_COPTS,
     visibility = ["//visibility:public"],
-    deps = [":upb"],
+    deps = [
+        ":mini_table_internal",
+        ":port",
+        ":upb",
+    ],
 )
 
 cc_test(
@@ -126,8 +140,10 @@ cc_test(
     srcs = ["upb/mini_table_test.cc"],
     deps = [
         ":mini_table",
-        "@com_google_googletest//:gtest_main",
+        ":mini_table_internal",
+        ":upb",
         "@com_google_absl//absl/container:flat_hash_set",
+        "@com_google_googletest//:gtest_main",
     ],
 )
 
@@ -458,6 +474,47 @@ sh_test(
     deps = ["@bazel_tools//tools/bash/runfiles"],
 )
 
+cc_binary(
+    name = "conformance_upb_dynamic_minitable",
+    testonly = 1,
+    srcs = ["upb/conformance_upb.c"],
+    copts = UPB_DEFAULT_COPTS + [
+        "-DREBUILD_MINITABLES",
+    ],
+    data = ["upb/conformance_upb_failures.txt"],
+    deps = [
+        ":conformance_proto_upb",
+        ":conformance_proto_upbdefs",
+        ":test_messages_proto2_upbdefs",
+        ":test_messages_proto3_upbdefs",
+        "//:json",
+        "//:port",
+        "//:reflection",
+        "//:textformat",
+        "//:upb",
+    ],
+)
+
+make_shell_script(
+    name = "gen_test_conformance_upb_dynamic_minitable",
+    out = "test_conformance_upb_dynamic_minitable.sh",
+    contents = "external/com_google_protobuf/conformance_test_runner " +
+               " --enforce_recommended " +
+               " --failure_list ./upb/conformance_upb_failures.txt" +
+               " ./conformance_upb_dynamic_minitable",
+)
+
+sh_test(
+    name = "test_conformance_upb_dynamic_minitable",
+    srcs = ["test_conformance_upb_dynamic_minitable.sh"],
+    data = [
+        "upb/conformance_upb_failures.txt",
+        ":conformance_upb_dynamic_minitable",
+        "@com_google_protobuf//:conformance_test_runner",
+    ],
+    deps = ["@bazel_tools//tools/bash/runfiles"],
+)
+
 # Internal C/C++ libraries #####################################################
 
 cc_library(
diff --git a/README.md b/README.md
index 92a081bbef..9b74b969ce 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,22 @@ For PHP, use [PECL](https://pecl.php.net/package/protobuf):
 $ sudo pecl install protobuf
 ```
 
+Alternatively, you can build and install upb using
+[vcpkg](https://github.com/microsoft/vcpkg/) dependency manager:
+
+    git clone https://github.com/Microsoft/vcpkg.git
+    cd vcpkg
+    ./bootstrap-vcpkg.sh
+    ./vcpkg integrate install
+    ./vcpkg install upb
+
+The upb port in vcpkg is kept up to date by microsoft team members and community
+contributors.
+
+If the version is out of date, please
+[create an issue or pull request](https://github.com/Microsoft/vcpkg) on the
+vcpkg repository.
+
 ## Contributing
 
 Please see [CONTRIBUTING.md](CONTRIBUTING.md).
diff --git a/bazel/amalgamate.py b/bazel/amalgamate.py
index 103b11c351..70399085ca 100755
--- a/bazel/amalgamate.py
+++ b/bazel/amalgamate.py
@@ -44,6 +44,9 @@ class Amalgamator:
 
     self.output_c.write("/* Amalgamated source file */\n")
     self.output_c.write('#include "%supb.h"\n' % (prefix))
+    if prefix == "ruby-":
+      self.output_h.write("// Ruby is still using proto3 enum semantics for proto2\n")
+      self.output_h.write("#define UPB_DISABLE_PROTO2_ENUM_CHECKING\n")
     self.output_c.write(open("upb/port_def.inc").read())
 
     self.output_h.write("/* Amalgamated source file */\n")
diff --git a/bazel/py_extension.bzl b/bazel/py_extension.bzl
index beee32148f..eacd39b856 100644
--- a/bazel/py_extension.bzl
+++ b/bazel/py_extension.bzl
@@ -1,10 +1,9 @@
-
 load(
     "//bazel:build_defs.bzl",
     "UPB_DEFAULT_COPTS",
 )
 
-def py_extension(name, srcs, deps=[]):
+def py_extension(name, srcs, deps = []):
     version_script = name + "_version_script.lds"
     symbol = "PyInit_" + name
     native.genrule(
diff --git a/bazel/pyproto_test_wrapper.bzl b/bazel/pyproto_test_wrapper.bzl
index fb909a1db8..e0d01ca225 100644
--- a/bazel/pyproto_test_wrapper.bzl
+++ b/bazel/pyproto_test_wrapper.bzl
@@ -1,4 +1,3 @@
-
 # copybara:strip_for_google3_begin
 
 def pyproto_test_wrapper(name):
diff --git a/benchmarks/build_defs.bzl b/benchmarks/build_defs.bzl
index f95a09ed1b..93da39f086 100644
--- a/benchmarks/build_defs.bzl
+++ b/benchmarks/build_defs.bzl
@@ -24,7 +24,7 @@
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 # copybara:insert_for_google3_begin
-# load("//tools/build_defs/proto/cpp:cc_proto_library.bzl", _cc_proto_library="cc_proto_library")
+# load("//tools/build_defs/proto/cpp:cc_proto_library.bzl", _cc_proto_library = "cc_proto_library")
 # copybara:insert_end
 
 # copybara:strip_for_google3_begin
@@ -36,7 +36,7 @@ def proto_library(**kwargs):
         # copybara:insert_for_google3_begin
         # cc_api_version = 2,
         # copybara:insert_end
-        **kwargs,
+        **kwargs
     )
 
 def tmpl_cc_binary(name, gen, args, replacements = [], **kwargs):
@@ -55,7 +55,7 @@ def tmpl_cc_binary(name, gen, args, replacements = [], **kwargs):
         # copybara:insert_end
         name = name,
         srcs = srcs,
-        **kwargs,
+        **kwargs
     )
 
 def cc_optimizefor_proto_library(name, srcs, outs, optimize_for):
diff --git a/benchmarks/compare.py b/benchmarks/compare.py
index 8c27ea72b4..445e61554d 100755
--- a/benchmarks/compare.py
+++ b/benchmarks/compare.py
@@ -81,7 +81,8 @@ def Benchmark(outbase, bench_cpu=True, runs=12, fasttable=False):
         print("{} {} {} ns/op".format(*values), file=f)
     Run("sort {} -o {} ".format(txt_filename, txt_filename))
 
-  Run("CC=clang bazel build -c opt --copt=-g --copt=-march=native :conformance_upb" + extra_args)
+  Run("CC=clang bazel build -c opt --copt=-g --copt=-march=native :conformance_upb"
+      + extra_args)
   Run("cp -f bazel-bin/conformance_upb {}.bin".format(outbase))
 
 
diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index a06bd604ac..8c08321eaa 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -81,11 +81,18 @@ target_link_libraries(upb
   fastdecode
   port
   /third_party/utf8_range)
+add_library(mini_table_internal INTERFACE)
+target_link_libraries(mini_table_internal INTERFACE
+  port
+  table
+  upb)
 add_library(mini_table
   ../upb/mini_table.c
   ../upb/mini_table.h
   ../upb/mini_table.hpp)
 target_link_libraries(mini_table
+  mini_table_internal
+  port
   upb)
 add_library(fastdecode
   ../upb/decode.h
diff --git a/upb/conformance_upb.c b/upb/conformance_upb.c
index 5f912f0c40..b64c112c86 100644
--- a/upb/conformance_upb.c
+++ b/upb/conformance_upb.c
@@ -323,8 +323,15 @@ bool DoTestIo(upb_DefPool* symtab) {
 int main(void) {
   upb_DefPool* symtab = upb_DefPool_New();
 
+#ifdef REBUILD_MINITABLES
+  _upb_DefPool_LoadDefInitEx(
+      symtab, &src_google_protobuf_test_messages_proto2_proto_upbdefinit, true);
+  _upb_DefPool_LoadDefInitEx(
+      symtab, &src_google_protobuf_test_messages_proto3_proto_upbdefinit, true);
+#else
   protobuf_test_messages_proto2_TestAllTypesProto2_getmsgdef(symtab);
   protobuf_test_messages_proto3_TestAllTypesProto3_getmsgdef(symtab);
+#endif
 
   while (1) {
     if (!DoTestIo(symtab)) {
diff --git a/upb/decode.c b/upb/decode.c
index 683e4ec32b..2d5bb49525 100644
--- a/upb/decode.c
+++ b/upb/decode.c
@@ -385,6 +385,18 @@ static char* encode_varint32(uint32_t val, char* ptr) {
   return ptr;
 }
 
+static void upb_Decode_AddUnknownVarints(upb_Decoder* d, upb_Message* msg,
+                                         uint32_t val1, uint32_t val2) {
+  char buf[20];
+  char* end = buf;
+  end = encode_varint32(val1, end);
+  end = encode_varint32(val2, end);
+
+  if (!_upb_Message_AddUnknown(msg, buf, end - buf, &d->arena)) {
+    decode_err(d, kUpb_DecodeStatus_OutOfMemory);
+  }
+}
+
 UPB_NOINLINE
 static bool decode_checkenum_slow(upb_Decoder* d, const char* ptr,
                                   upb_Message* msg, const upb_MiniTable_Enum* e,
@@ -398,17 +410,9 @@ static bool decode_checkenum_slow(upb_Decoder* d, const char* ptr,
 
   // Unrecognized enum goes into unknown fields.
   // For packed fields the tag could be arbitrarily far in the past, so we
-  // just re-encode the tag here.
-  char buf[20];
-  char* end = buf;
+  // just re-encode the tag and value here.
   uint32_t tag = ((uint32_t)field->number << 3) | kUpb_WireType_Varint;
-  end = encode_varint32(tag, end);
-  end = encode_varint32(v, end);
-
-  if (!_upb_Message_AddUnknown(msg, buf, end - buf, &d->arena)) {
-    decode_err(d, kUpb_DecodeStatus_OutOfMemory);
-  }
-
+  upb_Decode_AddUnknownVarints(d, msg, tag, v);
   return false;
 }
 
@@ -627,8 +631,20 @@ static const char* decode_tomap(upb_Decoder* d, const char* ptr,
         upb_value_ptr(_upb_Message_New(entry->subs[0].submsg, &d->arena));
   }
 
+  const char* start = ptr;
   ptr = decode_tosubmsg(d, ptr, &ent.k, subs, field, val->size);
-  _upb_Map_Set(map, &ent.k, map->key_size, &ent.v, map->val_size, &d->arena);
+  // check if ent had any unknown fields
+  size_t size;
+  upb_Message_GetUnknown(&ent.k, &size);
+  if (size != 0) {
+    uint32_t tag = ((uint32_t)field->number << 3) | kUpb_WireType_Delimited;
+    upb_Decode_AddUnknownVarints(d, msg, tag, (uint32_t)(ptr - start));
+    if (!_upb_Message_AddUnknown(msg, start, ptr - start, &d->arena)) {
+      decode_err(d, kUpb_DecodeStatus_OutOfMemory);
+    }
+  } else {
+    _upb_Map_Set(map, &ent.k, map->key_size, &ent.v, map->val_size, &d->arena);
+  }
   return ptr;
 }
 
diff --git a/upb/def.c b/upb/def.c
index 712d68d638..140465aab5 100644
--- a/upb/def.c
+++ b/upb/def.c
@@ -1413,7 +1413,12 @@ static uint8_t map_descriptortype(const upb_FieldDef* f) {
   if (type == kUpb_FieldType_String && f->file->syntax == kUpb_Syntax_Proto2) {
     return kUpb_FieldType_Bytes;
   } else if (type == kUpb_FieldType_Enum &&
-             f->sub.enumdef->file->syntax == kUpb_Syntax_Proto3) {
+             (f->sub.enumdef->file->syntax == kUpb_Syntax_Proto3 ||
+              UPB_TREAT_PROTO2_ENUMS_LIKE_PROTO3 ||
+              // TODO(https://github.com/protocolbuffers/upb/issues/541):
+              // fix map enum values to check for unknown enum values and put
+              // them in the unknown field set.
+              upb_MessageDef_IsMapEntry(upb_FieldDef_ContainingType(f)))) {
     return kUpb_FieldType_Int32;
   }
   return type;
@@ -1580,11 +1585,11 @@ static void make_layout(symtab_addctx* ctx, const upb_MessageDef* m) {
 
     fill_fieldlayout(field, f);
 
-    if (upb_FieldDef_IsSubMessage(f)) {
+    if (field->descriptortype == kUpb_FieldType_Message ||
+        field->descriptortype == kUpb_FieldType_Group) {
       field->submsg_index = sublayout_count++;
       subs[field->submsg_index].submsg = upb_FieldDef_MessageSubDef(f)->layout;
-    } else if (upb_FieldDef_CType(f) == kUpb_CType_Enum &&
-               f->sub.enumdef->file->syntax == kUpb_Syntax_Proto2) {
+    } else if (field->descriptortype == kUpb_FieldType_Enum) {
       field->submsg_index = sublayout_count++;
       subs[field->submsg_index].subenum = upb_FieldDef_EnumSubDef(f)->layout;
       UPB_ASSERT(subs[field->submsg_index].subenum);
diff --git a/upb/mini_table.c b/upb/mini_table.c
index 59d2c91a8c..471501fb1a 100644
--- a/upb/mini_table.c
+++ b/upb/mini_table.c
@@ -173,7 +173,7 @@ char* upb_MtDataEncoder_StartMessage(upb_MtDataEncoder* e, char* ptr,
 
 char* upb_MtDataEncoder_PutField(upb_MtDataEncoder* e, char* ptr,
                                  upb_FieldType type, uint32_t field_num,
-                                 uint64_t modifiers) {
+                                 uint64_t field_mod) {
   static const char kUpb_TypeToEncoded[] = {
       [kUpb_FieldType_Double] = kUpb_EncodedType_Double,
       [kUpb_FieldType_Float] = kUpb_EncodedType_Float,
@@ -209,7 +209,7 @@ char* upb_MtDataEncoder_PutField(upb_MtDataEncoder* e, char* ptr,
 
   // Put field type.
   int encoded_type = kUpb_TypeToEncoded[type];
-  if (modifiers & kUpb_FieldModifier_IsRepeated) {
+  if (field_mod & kUpb_FieldModifier_IsRepeated) {
     // Repeated fields shift the type number up (unlike other modifiers which
     // are bit flags).
     encoded_type += kUpb_EncodedType_RepeatedBase;
@@ -218,13 +218,13 @@ char* upb_MtDataEncoder_PutField(upb_MtDataEncoder* e, char* ptr,
   if (!ptr) return NULL;
 
   uint32_t encoded_modifiers = 0;
-  if (modifiers & kUpb_FieldModifier_IsProto3Singular) {
+  if (field_mod & kUpb_FieldModifier_IsProto3Singular) {
     encoded_modifiers |= kUpb_EncodedFieldModifier_IsProto3Singular;
   }
-  if (modifiers & kUpb_FieldModifier_IsRequired) {
+  if (field_mod & kUpb_FieldModifier_IsRequired) {
     encoded_modifiers |= kUpb_EncodedFieldModifier_IsRequired;
   }
-  if ((modifiers & kUpb_FieldModifier_IsPacked) !=
+  if ((field_mod & kUpb_FieldModifier_IsPacked) !=
       (in->msg_mod & kUpb_MessageModifier_DefaultIsPacked)) {
     encoded_modifiers |= kUpb_EncodedFieldModifier_IsUnpacked;
   }
diff --git a/upb/mini_table.h b/upb/mini_table.h
index e6cc886921..319c580843 100644
--- a/upb/mini_table.h
+++ b/upb/mini_table.h
@@ -1,9 +1,5 @@
 /*
-<<<<<<< HEAD
- * Copyright (c) 2009-2021, Google LLC
-=======
  * Copyright (c) 2009-2022, Google LLC
->>>>>>> mini-table-1
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -96,13 +92,13 @@ typedef struct {
 //   ptr = upb_MiniTable_PutOneofField(&e, ptr, ...);
 //
 // Oneofs must be encoded after all regular fields.
-char* upb_MtDataEncoder_StartMessage(upb_MtDataEncoder* e, char* buf,
+char* upb_MtDataEncoder_StartMessage(upb_MtDataEncoder* e, char* ptr,
                                      uint64_t msg_mod);
-char* upb_MtDataEncoder_PutField(upb_MtDataEncoder* e, char* buf,
+char* upb_MtDataEncoder_PutField(upb_MtDataEncoder* e, char* ptr,
                                  upb_FieldType type, uint32_t field_num,
                                  uint64_t field_mod);
-char* upb_MtDataEncoder_StartOneof(upb_MtDataEncoder* e, char* buf);
-char* upb_MtDataEncoder_PutOneofField(upb_MtDataEncoder* e, char* buf,
+char* upb_MtDataEncoder_StartOneof(upb_MtDataEncoder* e, char* ptr);
+char* upb_MtDataEncoder_PutOneofField(upb_MtDataEncoder* e, char* ptr,
                                       uint32_t field_num);
 
 /** upb_MiniTable *************************************************************/
diff --git a/upb/msg_test.cc b/upb/msg_test.cc
index cd6fdf67fb..2d1f8e991b 100644
--- a/upb/msg_test.cc
+++ b/upb/msg_test.cc
@@ -398,3 +398,32 @@ TEST(MessageTest, MaxRequiredFields) {
       test_msg, kUpb_Encode_CheckRequired, arena.ptr(), &size);
   ASSERT_TRUE(serialized != nullptr);
 }
+
+TEST(MessageTest, MapField) {
+  upb::Arena arena;
+  upb_test_TestMapFieldExtra* test_msg_extra =
+      upb_test_TestMapFieldExtra_new(arena.ptr());
+
+  ASSERT_TRUE(upb_test_TestMapFieldExtra_map_field_set(
+      test_msg_extra, 0, upb_test_TestMapFieldExtra_THREE, arena.ptr()));
+
+  size_t size;
+  char* serialized = upb_test_TestMapFieldExtra_serialize_ex(
+      test_msg_extra, 0, arena.ptr(), &size);
+  ASSERT_NE(nullptr, serialized);
+  ASSERT_NE(0, size);
+
+  upb_test_TestMapField* test_msg =
+      upb_test_TestMapField_parse(serialized, size, arena.ptr());
+  ASSERT_NE(nullptr, test_msg);
+
+  ASSERT_FALSE(upb_test_TestMapField_map_field_get(test_msg, 0, nullptr));
+  serialized =
+      upb_test_TestMapField_serialize_ex(test_msg, 0, arena.ptr(), &size);
+  ASSERT_NE(0, size);
+  // parse into second instance
+  upb_test_TestMapFieldExtra* test_msg_extra2 =
+      upb_test_TestMapFieldExtra_parse(serialized, size, arena.ptr());
+  ASSERT_TRUE(
+      upb_test_TestMapFieldExtra_map_field_get(test_msg_extra2, 0, nullptr));
+}
diff --git a/upb/msg_test.proto b/upb/msg_test.proto
index 81c7dee079..1f80f6918c 100644
--- a/upb/msg_test.proto
+++ b/upb/msg_test.proto
@@ -158,3 +158,22 @@ message TestMaxRequiredFields {
   required int32 required_int32_61 = 61;
   required int32 required_int32_62 = 62;
 }
+
+message TestMapField {
+  enum EnumMap {
+    ZERO = 0;
+    ONE = 1;
+    TWO = 2;
+  }
+  map<int32, EnumMap> map_field = 1;
+}
+
+message TestMapFieldExtra {
+  enum EnumMap {
+    ZERO = 0;
+    ONE = 1;
+    TWO = 2;
+    THREE = 3;
+  }
+  map<int32, EnumMap> map_field = 1;
+}
diff --git a/upb/port_def.inc b/upb/port_def.inc
index 75d416d1ce..2b240ff6e8 100644
--- a/upb/port_def.inc
+++ b/upb/port_def.inc
@@ -251,3 +251,11 @@ void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
 #define UPB_UNPOISON_MEMORY_REGION(addr, size) \
   ((void)(addr), (void)(size))
 #endif
+
+/* Disable proto2 arena behavior (TEMPORARY) **********************************/
+
+#ifdef UPB_DISABLE_PROTO2_ENUM_CHECKING
+#define UPB_TREAT_PROTO2_ENUMS_LIKE_PROTO3 1
+#else
+#define UPB_TREAT_PROTO2_ENUMS_LIKE_PROTO3 0
+#endif
diff --git a/upb/port_undef.inc b/upb/port_undef.inc
index 70956df25d..3ef2d0dbcd 100644
--- a/upb/port_undef.inc
+++ b/upb/port_undef.inc
@@ -59,3 +59,4 @@
 #undef UPB_POISON_MEMORY_REGION
 #undef UPB_UNPOISON_MEMORY_REGION
 #undef UPB_ASAN
+#undef UPB_TREAT_PROTO2_ENUMS_LIKE_PROTO3
diff --git a/upb/table.c b/upb/table.c
index 33b3a9dc6e..63fe3cc960 100644
--- a/upb/table.c
+++ b/upb/table.c
@@ -433,14 +433,14 @@ const uint64_t kWyhashSalt[5] = {
     0x082EFA98EC4E6C89ULL, 0x452821E638D01377ULL,
 };
 
-static uint32_t table_hash(const char* p, size_t n) {
+uint32_t _upb_Hash(const char* p, size_t n) {
   return Wyhash(p, n, 0, kWyhashSalt);
 }
 
 static uint32_t strhash(upb_tabkey key) {
   uint32_t len;
   char* str = upb_tabstr(key, &len);
-  return table_hash(str, len);
+  return _upb_Hash(str, len);
 }
 
 static bool streql(upb_tabkey k1, lookupkey_t k2) {
@@ -496,20 +496,20 @@ bool upb_strtable_insert(upb_strtable* t, const char* k, size_t len,
   tabkey = strcopy(key, a);
   if (tabkey == 0) return false;
 
-  hash = table_hash(key.str.str, key.str.len);
+  hash = _upb_Hash(key.str.str, key.str.len);
   insert(&t->t, key, tabkey, v, hash, &strhash, &streql);
   return true;
 }
 
 bool upb_strtable_lookup2(const upb_strtable* t, const char* key, size_t len,
                           upb_value* v) {
-  uint32_t hash = table_hash(key, len);
+  uint32_t hash = _upb_Hash(key, len);
   return lookup(&t->t, strkey2(key, len), v, hash, &streql);
 }
 
 bool upb_strtable_remove2(upb_strtable* t, const char* key, size_t len,
                           upb_value* val) {
-  uint32_t hash = table_hash(key, len);
+  uint32_t hash = _upb_Hash(key, len);
   upb_tabkey tabkey;
   return rm(&t->t, strkey2(key, len), val, &tabkey, hash, &streql);
 }
diff --git a/upb/table_internal.h b/upb/table_internal.h
index 9fb2d238cd..74076551de 100644
--- a/upb/table_internal.h
+++ b/upb/table_internal.h
@@ -374,6 +374,8 @@ void upb_inttable_iter_setdone(upb_inttable_iter* i);
 bool upb_inttable_iter_isequal(const upb_inttable_iter* i1,
                                const upb_inttable_iter* i2);
 
+uint32_t _upb_Hash(const char* p, size_t n);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif