diff --git a/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs b/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs
deleted file mode 100644
index 208ce1fcb631..000000000000
--- a/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-#region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-#endregion
-
-namespace Google.Protobuf.Reflection;
-
-internal sealed partial class FeatureSetDescriptor
-{
-    // Canonical serialized form of the edition defaults, generated by embed_edition_defaults.
-    private const string DefaultsBase64 =
-        "ChMYhAciACoMCAEQAhgCIAMoATACChMY5wciACoMCAIQARgBIAIoATABChMY6AciDAgBEAEYASACKAEwASoAIOYHKOgH";
-}
diff --git a/hpb/extension.h b/hpb/extension.h
index 6dea740af9b3..2cacc765426c 100644
--- a/hpb/extension.h
+++ b/hpb/extension.h
@@ -141,10 +141,23 @@ class ExtensionRegistry {
     }
   }
 
+  static const ExtensionRegistry& generated_registry() {
+    static const ExtensionRegistry* r = NewGeneratedRegistry();
+    return *r;
+  }
+
  private:
   friend upb_ExtensionRegistry* ::hpb::internal::GetUpbExtensions(
       const ExtensionRegistry& extension_registry);
   upb_ExtensionRegistry* registry_;
+
+  // TODO: b/379100963 - Introduce ShutdownHpbLibrary
+  static const ExtensionRegistry* NewGeneratedRegistry() {
+    static upb::Arena* global_arena = new upb::Arena();
+    ExtensionRegistry* registry = new ExtensionRegistry(*global_arena);
+    upb_ExtensionRegistry_AddAllLinkedExtensions(registry->registry_);
+    return registry;
+  }
 };
 
 template <typename T, typename Extendee, typename Extension,
diff --git a/hpb/internal/message_lock_test.cc b/hpb/internal/message_lock_test.cc
index a05e4a7bc78c..e28c79a9fbfb 100644
--- a/hpb/internal/message_lock_test.cc
+++ b/hpb/internal/message_lock_test.cc
@@ -122,12 +122,17 @@ TEST(CppGeneratedCode, ConcurrentAccessDoesNotRaceOneLazyOneEager) {
 }
 
 TEST(CppGeneratedCode, ConcurrentAccessDoesNotRaceBothEager) {
-  ::upb::Arena arena;
+  upb::Arena arena;
   hpb::ExtensionRegistry registry(arena);
   registry.AddExtension(theme);
   registry.AddExtension(ThemeExtension::theme_extension);
   TestConcurrentExtensionAccess(registry);
 }
 
+TEST(CppGeneratedCode, ConcurrentAccessDoesNotRaceGlobalInstance) {
+  upb::Arena arena;
+  TestConcurrentExtensionAccess(hpb::ExtensionRegistry::generated_registry());
+}
+
 }  // namespace
 }  // namespace hpb_unittest::protos
diff --git a/hpb_generator/tests/test_generated.cc b/hpb_generator/tests/test_generated.cc
index 6aa436646df0..497d36b1c3c3 100644
--- a/hpb_generator/tests/test_generated.cc
+++ b/hpb_generator/tests/test_generated.cc
@@ -1020,12 +1020,10 @@ TEST(CppGeneratedCode, ParseWithExtensionRegistry) {
   auto bytes = ::hpb::Serialize(&model, arena);
   EXPECT_EQ(true, bytes.ok());
 
-  hpb::ExtensionRegistry extensions(arena);
-  extensions.AddExtension(theme);
-  extensions.AddExtension(other_ext);
-  extensions.AddExtension(ThemeExtension::theme_extension);
   TestModel parsed_model =
-      ::hpb::Parse<TestModel>(bytes.value(), extensions).value();
+      ::hpb::Parse<TestModel>(bytes.value(),
+                              hpb::ExtensionRegistry::generated_registry())
+          .value();
   EXPECT_EQ("Test123", parsed_model.str1());
   EXPECT_EQ(true, hpb::GetExtension(&parsed_model, theme).ok());
   EXPECT_EQ(
@@ -1287,9 +1285,10 @@ TEST(CppGeneratedCode, HasExtensionAndRegistry) {
   std::string data = std::string(::hpb::Serialize(&source, arena).value());
 
   // Test with ExtensionRegistry
-  hpb::ExtensionRegistry extensions(arena);
-  extensions.AddExtension(theme);
-  TestModel parsed_model = ::hpb::Parse<TestModel>(data, extensions).value();
+  TestModel parsed_model =
+      ::hpb::Parse<TestModel>(data,
+                              hpb::ExtensionRegistry::generated_registry())
+          .value();
   EXPECT_TRUE(::hpb::HasExtension(&parsed_model, theme));
 }