diff --git a/conformance/BUILD.bazel b/conformance/BUILD.bazel
index ac007958c9..5330bf04d4 100644
--- a/conformance/BUILD.bazel
+++ b/conformance/BUILD.bazel
@@ -138,6 +138,7 @@ cc_library(
     includes = ["."],
     deps = [
         ":conformance_cc_proto",
+        "//src/google/protobuf:descriptor_legacy",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/strings:str_format",
     ],
diff --git a/conformance/conformance_test.cc b/conformance/conformance_test.cc
index aba07a0f1d..4d7f6dcc96 100644
--- a/conformance/conformance_test.cc
+++ b/conformance/conformance_test.cc
@@ -46,6 +46,7 @@
 #include "absl/strings/string_view.h"
 #include "conformance/conformance.pb.h"
 #include "conformance/conformance.pb.h"
+#include "google/protobuf/descriptor_legacy.h"
 
 using conformance::ConformanceRequest;
 using conformance::ConformanceResponse;
@@ -163,11 +164,12 @@ ConformanceTestSuite::ConformanceRequestSetting::NewTestMessage() const {
 
 string ConformanceTestSuite::ConformanceRequestSetting::GetTestName() const {
   string rname;
-  switch (prototype_message_.GetDescriptor()->file()->syntax()) {
-    case FileDescriptor::SYNTAX_PROTO3:
+  switch (FileDescriptorLegacy(prototype_message_.GetDescriptor()->file())
+              .syntax()) {
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO3:
       rname = ".Proto3.";
       break;
-    case FileDescriptor::SYNTAX_PROTO2:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO2:
       rname = ".Proto2.";
       break;
     default:
diff --git a/python/BUILD.bazel b/python/BUILD.bazel
index f6fe071152..d3f8cfb200 100644
--- a/python/BUILD.bazel
+++ b/python/BUILD.bazel
@@ -114,6 +114,7 @@ cc_binary(
     deps = [
         ":proto_api",
         "//:protobuf",
+        "//src/google/protobuf:descriptor_legacy",
     ] + select({
         "//conditions:default": [],
         ":use_fast_cpp_protos": ["//external:python_headers"],
diff --git a/python/google/protobuf/pyext/descriptor.cc b/python/google/protobuf/pyext/descriptor.cc
index de9a248073..c1fd20cdbb 100644
--- a/python/google/protobuf/pyext/descriptor.cc
+++ b/python/google/protobuf/pyext/descriptor.cc
@@ -33,6 +33,7 @@
 #include "google/protobuf/pyext/descriptor.h"
 
 #include "absl/log/absl_check.h"
+#include "google/protobuf/descriptor_legacy.h"
 
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
@@ -692,8 +693,9 @@ static PyObject* EnumValueName(PyBaseDescriptor *self, PyObject *args) {
 }
 
 static PyObject* GetSyntax(PyBaseDescriptor *self, void *closure) {
-  return PyUnicode_InternFromString(
-      FileDescriptor::SyntaxName(_GetDescriptor(self)->file()->syntax()));
+  std::string syntax(FileDescriptorLegacy::SyntaxName(
+      FileDescriptorLegacy(_GetDescriptor(self)->file()).syntax()));
+  return PyUnicode_InternFromString(syntax.c_str());
 }
 
 static PyGetSetDef Getters[] = {
@@ -1512,8 +1514,9 @@ static int SetSerializedOptions(PyFileDescriptor *self, PyObject *value,
 }
 
 static PyObject* GetSyntax(PyFileDescriptor *self, void *closure) {
-  return PyUnicode_InternFromString(
-      FileDescriptor::SyntaxName(_GetDescriptor(self)->syntax()));
+  std::string syntax(FileDescriptorLegacy::SyntaxName(
+      FileDescriptorLegacy(_GetDescriptor(self)).syntax()));
+  return PyUnicode_InternFromString(syntax.c_str());
 }
 
 static PyObject* CopyToProto(PyFileDescriptor *self, PyObject *target) {
diff --git a/src/google/protobuf/BUILD.bazel b/src/google/protobuf/BUILD.bazel
index 5744cc9ece..d76201d8f1 100644
--- a/src/google/protobuf/BUILD.bazel
+++ b/src/google/protobuf/BUILD.bazel
@@ -483,6 +483,9 @@ cc_library(
 cc_library(
     name = "descriptor_legacy",
     hdrs = ["descriptor_legacy.h"],
+    copts = COPTS,
+    include_prefix = "google/protobuf",
+    linkopts = LINK_OPTS,
     deps = [
         ":protobuf_nowkt",
         ":port_def",
diff --git a/src/google/protobuf/compiler/BUILD.bazel b/src/google/protobuf/compiler/BUILD.bazel
index c88020580e..7bbce08b4a 100644
--- a/src/google/protobuf/compiler/BUILD.bazel
+++ b/src/google/protobuf/compiler/BUILD.bazel
@@ -90,6 +90,7 @@ cc_library(
         ":code_generator",
         ":importer",
         ":retention",
+        "//src/google/protobuf:descriptor_legacy",
         "//src/google/protobuf:protobuf_nowkt",
         "//src/google/protobuf/compiler/allowlists",
         "@com_google_absl//absl/container:btree",
diff --git a/src/google/protobuf/compiler/command_line_interface.cc b/src/google/protobuf/compiler/command_line_interface.cc
index 86ae4b7cad..20d6d95e46 100644
--- a/src/google/protobuf/compiler/command_line_interface.cc
+++ b/src/google/protobuf/compiler/command_line_interface.cc
@@ -37,6 +37,7 @@
 #include "absl/container/btree_set.h"
 #include "absl/container/flat_hash_map.h"
 #include "google/protobuf/compiler/allowlists/allowlists.h"
+#include "google/protobuf/descriptor_legacy.h"
 
 #include "google/protobuf/stubs/platform_macros.h"
 
@@ -949,7 +950,7 @@ namespace {
 
 bool ContainsProto3Optional(const Descriptor* desc) {
   for (int i = 0; i < desc->field_count(); i++) {
-    if (desc->field(i)->has_optional_keyword()) {
+    if (FieldDescriptorLegacy(desc->field(i)).has_optional_keyword()) {
       return true;
     }
   }
@@ -962,7 +963,8 @@ bool ContainsProto3Optional(const Descriptor* desc) {
 }
 
 bool ContainsProto3Optional(const FileDescriptor* file) {
-  if (file->syntax() == FileDescriptor::SYNTAX_PROTO3) {
+  if (FileDescriptorLegacy(file).syntax() ==
+      FileDescriptorLegacy::Syntax::SYNTAX_PROTO3) {
     for (int i = 0; i < file->message_type_count(); i++) {
       if (ContainsProto3Optional(file->message_type(i))) {
         return true;
diff --git a/src/google/protobuf/compiler/objectivec/BUILD.bazel b/src/google/protobuf/compiler/objectivec/BUILD.bazel
index c3a3affd87..f78990394d 100644
--- a/src/google/protobuf/compiler/objectivec/BUILD.bazel
+++ b/src/google/protobuf/compiler/objectivec/BUILD.bazel
@@ -94,6 +94,7 @@ cc_library(
     deps = [
         ":line_consumer",
         ":names",
+        "//src/google/protobuf:descriptor_legacy",
         "//src/google/protobuf:protobuf_nowkt",
         "//src/google/protobuf/compiler:code_generator",
         "@com_google_absl//absl/container:btree",
diff --git a/src/google/protobuf/compiler/objectivec/file.cc b/src/google/protobuf/compiler/objectivec/file.cc
index 12b5de9626..385c0ebd86 100644
--- a/src/google/protobuf/compiler/objectivec/file.cc
+++ b/src/google/protobuf/compiler/objectivec/file.cc
@@ -50,6 +50,7 @@
 #include "google/protobuf/compiler/objectivec/message.h"
 #include "google/protobuf/compiler/objectivec/names.h"
 #include "google/protobuf/descriptor.h"
+#include "google/protobuf/descriptor_legacy.h"
 #include "google/protobuf/io/printer.h"
 
 // NOTE: src/google/protobuf/compiler/plugin.cc makes use of cerr for some
@@ -701,14 +702,14 @@ void FileGenerator::PrintFileDescription(io::Printer* p) const {
   vars["package_value"] = file_->package().empty()
                               ? "NULL"
                               : absl::StrCat("\"", file_->package(), "\"");
-  switch (file_->syntax()) {
-    case FileDescriptor::SYNTAX_UNKNOWN:
+  switch (FileDescriptorLegacy(file_).syntax()) {
+    case FileDescriptorLegacy::Syntax::SYNTAX_UNKNOWN:
       vars["syntax"] = "GPBFileSyntaxUnknown";
       break;
-    case FileDescriptor::SYNTAX_PROTO2:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO2:
       vars["syntax"] = "GPBFileSyntaxProto2";
       break;
-    case FileDescriptor::SYNTAX_PROTO3:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO3:
       vars["syntax"] = "GPBFileSyntaxProto3";
       break;
   }
diff --git a/src/google/protobuf/compiler/php/BUILD.bazel b/src/google/protobuf/compiler/php/BUILD.bazel
index 6d1fef5ba2..fe9e75c2c5 100644
--- a/src/google/protobuf/compiler/php/BUILD.bazel
+++ b/src/google/protobuf/compiler/php/BUILD.bazel
@@ -32,6 +32,7 @@ cc_library(
     ],
     deps = [
         ":names",
+        "//src/google/protobuf:descriptor_legacy",
         "//src/google/protobuf:protobuf_nowkt",
         "//src/google/protobuf/compiler:code_generator",
         "@com_google_absl//absl/strings",
diff --git a/src/google/protobuf/compiler/php/php_generator.cc b/src/google/protobuf/compiler/php/php_generator.cc
index b78ceef5ab..d8d1630e90 100644
--- a/src/google/protobuf/compiler/php/php_generator.cc
+++ b/src/google/protobuf/compiler/php/php_generator.cc
@@ -47,6 +47,7 @@
 #include "absl/strings/string_view.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
+#include "google/protobuf/descriptor_legacy.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/io/zero_copy_stream.h"
 
@@ -2292,7 +2293,9 @@ bool Generator::Generate(const FileDescriptor* file, const Options& options,
     return false;
   }
 
-  if (!options.is_descriptor && file->syntax() != FileDescriptor::SYNTAX_PROTO3) {
+  if (!options.is_descriptor &&
+      FileDescriptorLegacy(file).syntax() !=
+          FileDescriptorLegacy::Syntax::SYNTAX_PROTO3) {
     *error =
         "Can only generate PHP code for proto3 .proto files.\n"
         "Please add 'syntax = \"proto3\";' to the top of your .proto file.\n";
diff --git a/src/google/protobuf/compiler/python/BUILD.bazel b/src/google/protobuf/compiler/python/BUILD.bazel
index 90d5d21a85..5d26e0ce90 100644
--- a/src/google/protobuf/compiler/python/BUILD.bazel
+++ b/src/google/protobuf/compiler/python/BUILD.bazel
@@ -26,6 +26,7 @@ cc_library(
         "@com_github_grpc_grpc//tools/distrib/python/grpcio_tools:__subpackages__",
     ],
     deps = [
+        "//src/google/protobuf:descriptor_legacy",
         "//src/google/protobuf:protobuf_nowkt",
         "//src/google/protobuf/compiler:code_generator",
         "//src/google/protobuf/compiler:retention",
diff --git a/src/google/protobuf/compiler/python/generator.cc b/src/google/protobuf/compiler/python/generator.cc
index 651aaa9910..636808a3ae 100644
--- a/src/google/protobuf/compiler/python/generator.cc
+++ b/src/google/protobuf/compiler/python/generator.cc
@@ -67,6 +67,7 @@
 #include "google/protobuf/compiler/retention.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
+#include "google/protobuf/descriptor_legacy.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/io/strtod.h"
 #include "google/protobuf/io/zero_copy_stream.h"
@@ -173,13 +174,13 @@ std::string StringifyDefaultValue(const FieldDescriptor& field) {
   return "";
 }
 
-std::string StringifySyntax(FileDescriptor::Syntax syntax) {
+std::string StringifySyntax(FileDescriptorLegacy::Syntax syntax) {
   switch (syntax) {
-    case FileDescriptor::SYNTAX_PROTO2:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO2:
       return "proto2";
-    case FileDescriptor::SYNTAX_PROTO3:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO3:
       return "proto3";
-    case FileDescriptor::SYNTAX_UNKNOWN:
+    case FileDescriptorLegacy::Syntax::SYNTAX_UNKNOWN:
     default:
       ABSL_LOG(FATAL)
           << "Unsupported syntax; this generator only supports proto2 "
@@ -440,7 +441,7 @@ void Generator::PrintFileDescriptor() const {
   m["descriptor_name"] = kDescriptorKey;
   m["name"] = file_->name();
   m["package"] = file_->package();
-  m["syntax"] = StringifySyntax(file_->syntax());
+  m["syntax"] = StringifySyntax(FileDescriptorLegacy(file_).syntax());
   m["options"] = OptionsValue(
       StripLocalSourceRetentionOptions(*file_).SerializeAsString());
   m["serialized_descriptor"] = absl::CHexEscape(file_descriptor_serialized_);
@@ -690,7 +691,9 @@ void Generator::PrintDescriptor(const Descriptor& message_descriptor) const {
       "syntax='$syntax$'",
       "options_value", OptionsValue(options_string), "extendable",
       message_descriptor.extension_range_count() > 0 ? "True" : "False",
-      "syntax", StringifySyntax(message_descriptor.file()->syntax()));
+      "syntax",
+      StringifySyntax(
+          FileDescriptorLegacy(message_descriptor.file()).syntax()));
   printer_->Print(",\n");
 
   // Extension ranges
diff --git a/src/google/protobuf/compiler/ruby/BUILD.bazel b/src/google/protobuf/compiler/ruby/BUILD.bazel
index 47948416bc..520b691943 100644
--- a/src/google/protobuf/compiler/ruby/BUILD.bazel
+++ b/src/google/protobuf/compiler/ruby/BUILD.bazel
@@ -17,6 +17,7 @@ cc_library(
         "//src/google/protobuf/compiler:__pkg__",
     ],
     deps = [
+        "//src/google/protobuf:descriptor_legacy",
         "//src/google/protobuf:protobuf_nowkt",
         "//src/google/protobuf/compiler:code_generator",
     ],
diff --git a/src/google/protobuf/compiler/ruby/ruby_generator.cc b/src/google/protobuf/compiler/ruby/ruby_generator.cc
index 5013fbd584..625c5004d4 100644
--- a/src/google/protobuf/compiler/ruby/ruby_generator.cc
+++ b/src/google/protobuf/compiler/ruby/ruby_generator.cc
@@ -39,6 +39,7 @@
 #include "google/protobuf/compiler/plugin.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
+#include "google/protobuf/descriptor_legacy.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/io/zero_copy_stream.h"
 
@@ -79,7 +80,8 @@ std::string GetOutputFilename(absl::string_view proto_file) {
 }
 
 std::string LabelForField(const FieldDescriptor* field) {
-  if (field->has_optional_keyword() && field->containing_oneof() != nullptr) {
+  if (FieldDescriptorLegacy(field).has_optional_keyword() &&
+      field->containing_oneof() != nullptr) {
     return "proto3_optional";
   }
   switch (field->label()) {
@@ -114,13 +116,13 @@ std::string TypeName(const FieldDescriptor* field) {
   }
 }
 
-std::string StringifySyntax(FileDescriptor::Syntax syntax) {
+std::string StringifySyntax(FileDescriptorLegacy::Syntax syntax) {
   switch (syntax) {
-    case FileDescriptor::SYNTAX_PROTO2:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO2:
       return "proto2";
-    case FileDescriptor::SYNTAX_PROTO3:
+    case FileDescriptorLegacy::Syntax::SYNTAX_PROTO3:
       return "proto3";
-    case FileDescriptor::SYNTAX_UNKNOWN:
+    case FileDescriptorLegacy::Syntax::SYNTAX_UNKNOWN:
     default:
       ABSL_LOG(FATAL) << "Unsupported syntax; this generator only supports "
                          "proto2 and proto3 syntax.";
@@ -474,7 +476,7 @@ bool GenerateDslDescriptor(const FileDescriptor* file, io::Printer* printer,
   printer->Indent();
   printer->Print("add_file(\"$filename$\", :syntax => :$syntax$) do\n",
                  "filename", file->name(), "syntax",
-                 StringifySyntax(file->syntax()));
+                 StringifySyntax(FileDescriptorLegacy(file).syntax()));
   printer->Indent();
   for (int i = 0; i < file->message_type_count(); i++) {
     if (!GenerateMessage(file->message_type(i), printer, error)) {
@@ -557,7 +559,8 @@ bool Generator::Generate(
     const std::string& parameter,
     GeneratorContext* generator_context,
     std::string* error) const {
-  if (file->syntax() == FileDescriptor::SYNTAX_UNKNOWN) {
+  if (FileDescriptorLegacy(file).syntax() ==
+      FileDescriptorLegacy::Syntax::SYNTAX_UNKNOWN) {
     *error = "Invalid or unsupported proto syntax";
     return false;
   }
diff --git a/src/google/protobuf/util/BUILD.bazel b/src/google/protobuf/util/BUILD.bazel
index 609a86a27b..d25694c7c0 100644
--- a/src/google/protobuf/util/BUILD.bazel
+++ b/src/google/protobuf/util/BUILD.bazel
@@ -169,6 +169,7 @@ cc_library(
     visibility = ["//:__subpackages__"],
     deps = [
         "//src/google/protobuf",
+        "//src/google/protobuf:descriptor_legacy",
         "//src/google/protobuf/io",
         "//src/google/protobuf/stubs",
         "@com_google_absl//absl/log:absl_log",
diff --git a/src/google/protobuf/util/type_resolver_util.cc b/src/google/protobuf/util/type_resolver_util.cc
index e408e78b89..c326aa29c7 100644
--- a/src/google/protobuf/util/type_resolver_util.cc
+++ b/src/google/protobuf/util/type_resolver_util.cc
@@ -43,6 +43,7 @@
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "absl/strings/strip.h"
+#include "google/protobuf/descriptor_legacy.h"
 #include "google/protobuf/io/strtod.h"
 #include "google/protobuf/util/type_resolver.h"
 
@@ -273,7 +274,7 @@ void ConvertFieldDescriptor(absl::string_view url_prefix,
   ConvertFieldOptions(descriptor.options(), *field->mutable_options());
 }
 
-Syntax ConvertSyntax(FileDescriptor::Syntax syntax) {
+Syntax ConvertSyntax(FileDescriptorLegacy::Syntax syntax) {
   switch (syntax) {
     default:
       return Syntax::SYNTAX_PROTO2;
@@ -282,7 +283,8 @@ Syntax ConvertSyntax(FileDescriptor::Syntax syntax) {
 
 void ConvertEnumDescriptor(const EnumDescriptor& descriptor, Enum* enum_type) {
   enum_type->Clear();
-  enum_type->set_syntax(ConvertSyntax(descriptor.file()->syntax()));
+  enum_type->set_syntax(
+      ConvertSyntax(FileDescriptorLegacy(descriptor.file()).syntax()));
 
   enum_type->set_name(descriptor.full_name());
   enum_type->mutable_source_context()->set_file_name(descriptor.file()->name());
@@ -303,7 +305,8 @@ void ConvertDescriptor(absl::string_view url_prefix,
                        const Descriptor& descriptor, Type* type) {
   type->Clear();
   type->set_name(descriptor.full_name());
-  type->set_syntax(ConvertSyntax(descriptor.file()->syntax()));
+  type->set_syntax(
+      ConvertSyntax(FileDescriptorLegacy(descriptor.file()).syntax()));
   for (int i = 0; i < descriptor.field_count(); ++i) {
     ConvertFieldDescriptor(url_prefix, *descriptor.field(i),
                            type->add_fields());
diff --git a/src/google/protobuf/util/type_resolver_util_test.cc b/src/google/protobuf/util/type_resolver_util_test.cc
index eaf6649f00..00391693ff 100644
--- a/src/google/protobuf/util/type_resolver_util_test.cc
+++ b/src/google/protobuf/util/type_resolver_util_test.cc
@@ -44,6 +44,7 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 #include "google/protobuf/descriptor.h"
+#include "google/protobuf/descriptor_legacy.h"
 #include "google/protobuf/util/json_format_proto3.pb.h"
 #include "google/protobuf/map_unittest.pb.h"
 #include "google/protobuf/unittest.pb.h"
@@ -466,7 +467,8 @@ class DescriptorPoolTypeResolverSyntaxTest : public testing::Test {
 
 TEST_F(DescriptorPoolTypeResolverSyntaxTest, SyntaxProto2) {
   const FileDescriptor* file = BuildFile("proto2");
-  ASSERT_EQ(FileDescriptor::SYNTAX_PROTO2, file->syntax());
+  ASSERT_EQ(FileDescriptorLegacy::Syntax::SYNTAX_PROTO2,
+            FileDescriptorLegacy(file).syntax());
 
   Type type;
   ASSERT_TRUE(
@@ -477,7 +479,8 @@ TEST_F(DescriptorPoolTypeResolverSyntaxTest, SyntaxProto2) {
 
 TEST_F(DescriptorPoolTypeResolverSyntaxTest, SyntaxProto3) {
   const FileDescriptor* file = BuildFile("proto3");
-  ASSERT_EQ(FileDescriptor::SYNTAX_PROTO3, file->syntax());
+  ASSERT_EQ(FileDescriptorLegacy::Syntax::SYNTAX_PROTO3,
+            FileDescriptorLegacy(file).syntax());
 
   Type type;
   ASSERT_TRUE(