diff --git a/src/google/protobuf/compiler/cpp/message.cc b/src/google/protobuf/compiler/cpp/message.cc
index b033b06699..5411768d55 100644
--- a/src/google/protobuf/compiler/cpp/message.cc
+++ b/src/google/protobuf/compiler/cpp/message.cc
@@ -1558,14 +1558,16 @@ void MessageGenerator::GenerateClassDefinition(io::Printer* p) {
   }
 
   if (!HasSimpleBaseClass(descriptor_, options_)) {
-    format(
-        "int GetCachedSize() const final { return "
-        "$cached_size$.Get(); }"
-        "\n\nprivate:\n"
-        "void SharedCtor(::$proto_ns$::Arena* arena);\n"
-        "void SharedDtor();\n"
-        "void SetCachedSize(int size) const$ full_final$;\n"
-        "void InternalSwap($classname$* other);\n");
+    p->Emit(
+        R"cc(
+          int GetCachedSize() const { return $cached_size$.Get(); }
+
+          private:
+          $pbi$::CachedSize* AccessCachedSize() const final;
+          void SharedCtor(::$proto_ns$::Arena* arena);
+          void SharedDtor();
+          void InternalSwap($classname$* other);
+        )cc");
   }
 
   format(
@@ -2100,6 +2102,14 @@ void MessageGenerator::GenerateClassMethods(io::Printer* p) {
         DefaultInstanceName(descriptor_, options_, /*split=*/false));
   }
 
+  if (!HasSimpleBaseClass(descriptor_, options_)) {
+    p->Emit(R"cc(
+      ::_pbi::CachedSize* $classname$::AccessCachedSize() const {
+        return &$cached_size$;
+      }
+    )cc");
+  }
+
   GenerateVerify(p);
 
   GenerateSwap(p);
@@ -3515,15 +3525,6 @@ void MessageGenerator::GenerateStructors(io::Printer* p) {
   if (NeedsArenaDestructor() > ArenaDtorNeeds::kNone) {
     GenerateArenaDestructorCode(p);
   }
-
-  if (!HasSimpleBaseClass(descriptor_, options_)) {
-    // Generate SetCachedSize.
-    p->Emit(R"cc(
-      void $classname$::SetCachedSize(int size) const {
-        $cached_size$.Set(size);
-      }
-    )cc");
-  }
 }
 
 void MessageGenerator::GenerateSourceInProto2Namespace(io::Printer* p) {
@@ -4731,8 +4732,7 @@ void MessageGenerator::GenerateByteSize(io::Printer* p) {
             if ($have_unknown_fields$) {
               total_size += ::_pbi::ComputeUnknownMessageSetItemsSize($unknown_fields$);
             }
-            int cached_size = ::_pbi::ToCachedSize(total_size);
-            SetCachedSize(cached_size);
+            $cached_size$.Set(::_pbi::ToCachedSize(total_size));
             return total_size;
           }
         )cc");
@@ -4900,10 +4900,10 @@ void MessageGenerator::GenerateByteSize(io::Printer* p) {
     // abstract away the underlying atomic. This makes it easier on platforms
     // where even relaxed memory order might have perf impact to replace it with
     // ordinary loads and stores.
-    format(
-        "int cached_size = ::_pbi::ToCachedSize(total_size);\n"
-        "SetCachedSize(cached_size);\n"
-        "return total_size;\n");
+    p->Emit(R"cc(
+      $cached_size$.Set(::_pbi::ToCachedSize(total_size));
+      return total_size;
+    )cc");
   }
 
   format.Outdent();
diff --git a/src/google/protobuf/compiler/plugin.pb.cc b/src/google/protobuf/compiler/plugin.pb.cc
index 83ae35b759..2c874eff87 100644
--- a/src/google/protobuf/compiler/plugin.pb.cc
+++ b/src/google/protobuf/compiler/plugin.pb.cc
@@ -375,9 +375,6 @@ inline void Version::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   _impl_.suffix_.Destroy();
 }
-void Version::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void Version::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.compiler.Version)
@@ -586,6 +583,9 @@ PROTOBUF_NOINLINE bool Version::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* Version::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void Version::InternalSwap(Version* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -695,9 +695,6 @@ inline void CodeGeneratorRequest::SharedDtor() {
   _impl_.parameter_.Destroy();
   if (this != internal_default_instance()) delete _impl_.compiler_version_;
 }
-void CodeGeneratorRequest::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void CodeGeneratorRequest::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.compiler.CodeGeneratorRequest)
@@ -940,6 +937,9 @@ PROTOBUF_NOINLINE bool CodeGeneratorRequest::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* CodeGeneratorRequest::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void CodeGeneratorRequest::InternalSwap(CodeGeneratorRequest* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -1069,9 +1069,6 @@ inline void CodeGeneratorResponse_File::SharedDtor() {
   _impl_.content_.Destroy();
   if (this != internal_default_instance()) delete _impl_.generated_code_info_;
 }
-void CodeGeneratorResponse_File::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void CodeGeneratorResponse_File::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.compiler.CodeGeneratorResponse.File)
@@ -1292,6 +1289,9 @@ PROTOBUF_NOINLINE bool CodeGeneratorResponse_File::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* CodeGeneratorResponse_File::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void CodeGeneratorResponse_File::InternalSwap(CodeGeneratorResponse_File* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -1379,9 +1379,6 @@ inline void CodeGeneratorResponse::SharedDtor() {
   _impl_.file_.~RepeatedPtrField();
   _impl_.error_.Destroy();
 }
-void CodeGeneratorResponse::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void CodeGeneratorResponse::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.compiler.CodeGeneratorResponse)
@@ -1566,6 +1563,9 @@ PROTOBUF_NOINLINE bool CodeGeneratorResponse::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* CodeGeneratorResponse::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void CodeGeneratorResponse::InternalSwap(CodeGeneratorResponse* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
diff --git a/src/google/protobuf/compiler/plugin.pb.h b/src/google/protobuf/compiler/plugin.pb.h
index 14f788a75a..d37d1ef779 100644
--- a/src/google/protobuf/compiler/plugin.pb.h
+++ b/src/google/protobuf/compiler/plugin.pb.h
@@ -226,12 +226,12 @@ class PROTOC_EXPORT Version final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(Version* other);
 
   private:
@@ -440,12 +440,12 @@ class PROTOC_EXPORT CodeGeneratorResponse_File final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(CodeGeneratorResponse_File* other);
 
   private:
@@ -670,12 +670,12 @@ class PROTOC_EXPORT CodeGeneratorResponse final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(CodeGeneratorResponse* other);
 
   private:
@@ -901,12 +901,12 @@ class PROTOC_EXPORT CodeGeneratorRequest final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(CodeGeneratorRequest* other);
 
   private:
diff --git a/src/google/protobuf/cpp_features.pb.cc b/src/google/protobuf/cpp_features.pb.cc
index 2cfc851929..442d1e0561 100644
--- a/src/google/protobuf/cpp_features.pb.cc
+++ b/src/google/protobuf/cpp_features.pb.cc
@@ -183,9 +183,6 @@ CppFeatures::~CppFeatures() {
 inline void CppFeatures::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
 }
-void CppFeatures::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void CppFeatures::Clear() {
 // @@protoc_insertion_point(message_clear_start:pb.CppFeatures)
@@ -342,6 +339,9 @@ PROTOBUF_NOINLINE bool CppFeatures::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* CppFeatures::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void CppFeatures::InternalSwap(CppFeatures* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
diff --git a/src/google/protobuf/cpp_features.pb.h b/src/google/protobuf/cpp_features.pb.h
index 5ef9becdaa..3ff982684a 100644
--- a/src/google/protobuf/cpp_features.pb.h
+++ b/src/google/protobuf/cpp_features.pb.h
@@ -210,12 +210,12 @@ class PROTOBUF_EXPORT CppFeatures final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(CppFeatures* other);
 
   private:
diff --git a/src/google/protobuf/descriptor.pb.cc b/src/google/protobuf/descriptor.pb.cc
index c20b58d20a..5e6af5404b 100644
--- a/src/google/protobuf/descriptor.pb.cc
+++ b/src/google/protobuf/descriptor.pb.cc
@@ -2331,9 +2331,6 @@ inline void FileDescriptorSet::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   _impl_.file_.~RepeatedPtrField();
 }
-void FileDescriptorSet::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FileDescriptorSet::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FileDescriptorSet)
@@ -2456,6 +2453,9 @@ PROTOBUF_NOINLINE bool FileDescriptorSet::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FileDescriptorSet::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FileDescriptorSet::InternalSwap(FileDescriptorSet* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
@@ -2623,9 +2623,6 @@ inline void FileDescriptorProto::SharedDtor() {
   if (this != internal_default_instance()) delete _impl_.options_;
   if (this != internal_default_instance()) delete _impl_.source_code_info_;
 }
-void FileDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FileDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FileDescriptorProto)
@@ -3084,6 +3081,9 @@ PROTOBUF_NOINLINE bool FileDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FileDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FileDescriptorProto::InternalSwap(FileDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -3185,9 +3185,6 @@ inline void DescriptorProto_ExtensionRange::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void DescriptorProto_ExtensionRange::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void DescriptorProto_ExtensionRange::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.DescriptorProto.ExtensionRange)
@@ -3376,6 +3373,9 @@ PROTOBUF_NOINLINE bool DescriptorProto_ExtensionRange::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* DescriptorProto_ExtensionRange::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void DescriptorProto_ExtensionRange::InternalSwap(DescriptorProto_ExtensionRange* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
@@ -3436,9 +3436,6 @@ DescriptorProto_ReservedRange::~DescriptorProto_ReservedRange() {
 inline void DescriptorProto_ReservedRange::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
 }
-void DescriptorProto_ReservedRange::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void DescriptorProto_ReservedRange::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.DescriptorProto.ReservedRange)
@@ -3595,6 +3592,9 @@ PROTOBUF_NOINLINE bool DescriptorProto_ReservedRange::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* DescriptorProto_ReservedRange::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void DescriptorProto_ReservedRange::InternalSwap(DescriptorProto_ReservedRange* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
@@ -3707,9 +3707,6 @@ inline void DescriptorProto::SharedDtor() {
   _impl_.name_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void DescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void DescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.DescriptorProto)
@@ -4087,6 +4084,9 @@ PROTOBUF_NOINLINE bool DescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* DescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void DescriptorProto::InternalSwap(DescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -4204,9 +4204,6 @@ inline void ExtensionRangeOptions_Declaration::SharedDtor() {
   _impl_.full_name_.Destroy();
   _impl_.type_.Destroy();
 }
-void ExtensionRangeOptions_Declaration::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void ExtensionRangeOptions_Declaration::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.ExtensionRangeOptions.Declaration)
@@ -4444,6 +4441,9 @@ PROTOBUF_NOINLINE bool ExtensionRangeOptions_Declaration::IsInitialized() const
   return true;
 }
 
+::_pbi::CachedSize* ExtensionRangeOptions_Declaration::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void ExtensionRangeOptions_Declaration::InternalSwap(ExtensionRangeOptions_Declaration* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -4538,9 +4538,6 @@ inline void ExtensionRangeOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void ExtensionRangeOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void ExtensionRangeOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.ExtensionRangeOptions)
@@ -4770,6 +4767,9 @@ PROTOBUF_NOINLINE bool ExtensionRangeOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* ExtensionRangeOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void ExtensionRangeOptions::InternalSwap(ExtensionRangeOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -4957,9 +4957,6 @@ inline void FieldDescriptorProto::SharedDtor() {
   _impl_.json_name_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void FieldDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FieldDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FieldDescriptorProto)
@@ -5366,6 +5363,9 @@ PROTOBUF_NOINLINE bool FieldDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FieldDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FieldDescriptorProto::InternalSwap(FieldDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -5466,9 +5466,6 @@ inline void OneofDescriptorProto::SharedDtor() {
   _impl_.name_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void OneofDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void OneofDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.OneofDescriptorProto)
@@ -5637,6 +5634,9 @@ PROTOBUF_NOINLINE bool OneofDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* OneofDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void OneofDescriptorProto::InternalSwap(OneofDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -5696,9 +5696,6 @@ EnumDescriptorProto_EnumReservedRange::~EnumDescriptorProto_EnumReservedRange()
 inline void EnumDescriptorProto_EnumReservedRange::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
 }
-void EnumDescriptorProto_EnumReservedRange::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void EnumDescriptorProto_EnumReservedRange::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.EnumDescriptorProto.EnumReservedRange)
@@ -5855,6 +5852,9 @@ PROTOBUF_NOINLINE bool EnumDescriptorProto_EnumReservedRange::IsInitialized() co
   return true;
 }
 
+::_pbi::CachedSize* EnumDescriptorProto_EnumReservedRange::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void EnumDescriptorProto_EnumReservedRange::InternalSwap(EnumDescriptorProto_EnumReservedRange* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
@@ -5952,9 +5952,6 @@ inline void EnumDescriptorProto::SharedDtor() {
   _impl_.name_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void EnumDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void EnumDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.EnumDescriptorProto)
@@ -6199,6 +6196,9 @@ PROTOBUF_NOINLINE bool EnumDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* EnumDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void EnumDescriptorProto::InternalSwap(EnumDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -6295,9 +6295,6 @@ inline void EnumValueDescriptorProto::SharedDtor() {
   _impl_.name_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void EnumValueDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void EnumValueDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.EnumValueDescriptorProto)
@@ -6491,6 +6488,9 @@ PROTOBUF_NOINLINE bool EnumValueDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* EnumValueDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void EnumValueDescriptorProto::InternalSwap(EnumValueDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -6586,9 +6586,6 @@ inline void ServiceDescriptorProto::SharedDtor() {
   _impl_.name_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void ServiceDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void ServiceDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.ServiceDescriptorProto)
@@ -6784,6 +6781,9 @@ PROTOBUF_NOINLINE bool ServiceDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* ServiceDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void ServiceDescriptorProto::InternalSwap(ServiceDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -6919,9 +6919,6 @@ inline void MethodDescriptorProto::SharedDtor() {
   _impl_.output_type_.Destroy();
   if (this != internal_default_instance()) delete _impl_.options_;
 }
-void MethodDescriptorProto::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void MethodDescriptorProto::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.MethodDescriptorProto)
@@ -7192,6 +7189,9 @@ PROTOBUF_NOINLINE bool MethodDescriptorProto::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* MethodDescriptorProto::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void MethodDescriptorProto::InternalSwap(MethodDescriptorProto* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -7502,9 +7502,6 @@ inline void FileOptions::SharedDtor() {
   _impl_.ruby_package_.Destroy();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void FileOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FileOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FileOptions)
@@ -8193,6 +8190,9 @@ PROTOBUF_NOINLINE bool FileOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FileOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FileOptions::InternalSwap(FileOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -8324,9 +8324,6 @@ inline void MessageOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void MessageOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void MessageOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.MessageOptions)
@@ -8610,6 +8607,9 @@ PROTOBUF_NOINLINE bool MessageOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* MessageOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void MessageOptions::InternalSwap(MessageOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -8704,9 +8704,6 @@ inline void FieldOptions_EditionDefault::SharedDtor() {
   _impl_.edition_.Destroy();
   _impl_.value_.Destroy();
 }
-void FieldOptions_EditionDefault::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FieldOptions_EditionDefault::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FieldOptions.EditionDefault)
@@ -8871,6 +8868,9 @@ PROTOBUF_NOINLINE bool FieldOptions_EditionDefault::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FieldOptions_EditionDefault::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FieldOptions_EditionDefault::InternalSwap(FieldOptions_EditionDefault* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -9004,9 +9004,6 @@ inline void FieldOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void FieldOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FieldOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FieldOptions)
@@ -9443,6 +9440,9 @@ PROTOBUF_NOINLINE bool FieldOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FieldOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FieldOptions::InternalSwap(FieldOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -9526,9 +9526,6 @@ inline void OneofOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void OneofOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void OneofOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.OneofOptions)
@@ -9701,6 +9698,9 @@ PROTOBUF_NOINLINE bool OneofOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* OneofOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void OneofOptions::InternalSwap(OneofOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -9795,9 +9795,6 @@ inline void EnumOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void EnumOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void EnumOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.EnumOptions)
@@ -10041,6 +10038,9 @@ PROTOBUF_NOINLINE bool EnumOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* EnumOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void EnumOptions::InternalSwap(EnumOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -10135,9 +10135,6 @@ inline void EnumValueOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void EnumValueOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void EnumValueOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.EnumValueOptions)
@@ -10363,6 +10360,9 @@ PROTOBUF_NOINLINE bool EnumValueOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* EnumValueOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void EnumValueOptions::InternalSwap(EnumValueOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -10450,9 +10450,6 @@ inline void ServiceOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void ServiceOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void ServiceOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.ServiceOptions)
@@ -10653,6 +10650,9 @@ PROTOBUF_NOINLINE bool ServiceOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* ServiceOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void ServiceOptions::InternalSwap(ServiceOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -10747,9 +10747,6 @@ inline void MethodOptions::SharedDtor() {
   _impl_.uninterpreted_option_.~RepeatedPtrField();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void MethodOptions::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void MethodOptions::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.MethodOptions)
@@ -10980,6 +10977,9 @@ PROTOBUF_NOINLINE bool MethodOptions::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* MethodOptions::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void MethodOptions::InternalSwap(MethodOptions* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -11066,9 +11066,6 @@ inline void UninterpretedOption_NamePart::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   _impl_.name_part_.Destroy();
 }
-void UninterpretedOption_NamePart::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void UninterpretedOption_NamePart::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.UninterpretedOption.NamePart)
@@ -11230,6 +11227,9 @@ PROTOBUF_NOINLINE bool UninterpretedOption_NamePart::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* UninterpretedOption_NamePart::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void UninterpretedOption_NamePart::InternalSwap(UninterpretedOption_NamePart* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -11359,9 +11359,6 @@ inline void UninterpretedOption::SharedDtor() {
   _impl_.string_value_.Destroy();
   _impl_.aggregate_value_.Destroy();
 }
-void UninterpretedOption::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void UninterpretedOption::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.UninterpretedOption)
@@ -11647,6 +11644,9 @@ PROTOBUF_NOINLINE bool UninterpretedOption::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* UninterpretedOption::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void UninterpretedOption::InternalSwap(UninterpretedOption* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -11747,9 +11747,6 @@ inline void FeatureSet::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   _impl_._extensions_.~ExtensionSet();
 }
-void FeatureSet::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FeatureSet::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FeatureSet)
@@ -11989,6 +11986,9 @@ PROTOBUF_NOINLINE bool FeatureSet::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FeatureSet::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FeatureSet::InternalSwap(FeatureSet* other) {
   using std::swap;
   _impl_._extensions_.InternalSwap(&other->_impl_._extensions_);
@@ -12078,9 +12078,6 @@ inline void FeatureSetDefaults_FeatureSetEditionDefault::SharedDtor() {
   _impl_.edition_.Destroy();
   if (this != internal_default_instance()) delete _impl_.features_;
 }
-void FeatureSetDefaults_FeatureSetEditionDefault::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FeatureSetDefaults_FeatureSetEditionDefault::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FeatureSetDefaults.FeatureSetEditionDefault)
@@ -12249,6 +12246,9 @@ PROTOBUF_NOINLINE bool FeatureSetDefaults_FeatureSetEditionDefault::IsInitialize
   return true;
 }
 
+::_pbi::CachedSize* FeatureSetDefaults_FeatureSetEditionDefault::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FeatureSetDefaults_FeatureSetEditionDefault::InternalSwap(FeatureSetDefaults_FeatureSetEditionDefault* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -12343,9 +12343,6 @@ inline void FeatureSetDefaults::SharedDtor() {
   _impl_.minimum_edition_.Destroy();
   _impl_.maximum_edition_.Destroy();
 }
-void FeatureSetDefaults::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void FeatureSetDefaults::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.FeatureSetDefaults)
@@ -12536,6 +12533,9 @@ PROTOBUF_NOINLINE bool FeatureSetDefaults::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* FeatureSetDefaults::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void FeatureSetDefaults::InternalSwap(FeatureSetDefaults* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -12642,9 +12642,6 @@ inline void SourceCodeInfo_Location::SharedDtor() {
   _impl_.leading_comments_.Destroy();
   _impl_.trailing_comments_.Destroy();
 }
-void SourceCodeInfo_Location::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void SourceCodeInfo_Location::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.SourceCodeInfo.Location)
@@ -12895,6 +12892,9 @@ PROTOBUF_NOINLINE bool SourceCodeInfo_Location::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* SourceCodeInfo_Location::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void SourceCodeInfo_Location::InternalSwap(SourceCodeInfo_Location* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -12954,9 +12954,6 @@ inline void SourceCodeInfo::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   _impl_.location_.~RepeatedPtrField();
 }
-void SourceCodeInfo::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void SourceCodeInfo::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.SourceCodeInfo)
@@ -13077,6 +13074,9 @@ PROTOBUF_NOINLINE bool SourceCodeInfo::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* SourceCodeInfo::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void SourceCodeInfo::InternalSwap(SourceCodeInfo* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
@@ -13169,9 +13169,6 @@ inline void GeneratedCodeInfo_Annotation::SharedDtor() {
   _impl_.path_.~RepeatedField();
   _impl_.source_file_.Destroy();
 }
-void GeneratedCodeInfo_Annotation::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void GeneratedCodeInfo_Annotation::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.GeneratedCodeInfo.Annotation)
@@ -13412,6 +13409,9 @@ PROTOBUF_NOINLINE bool GeneratedCodeInfo_Annotation::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* GeneratedCodeInfo_Annotation::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void GeneratedCodeInfo_Annotation::InternalSwap(GeneratedCodeInfo_Annotation* other) {
   using std::swap;
   auto* lhs_arena = GetArenaForAllocation();
@@ -13473,9 +13473,6 @@ inline void GeneratedCodeInfo::SharedDtor() {
   ABSL_DCHECK(GetArenaForAllocation() == nullptr);
   _impl_.annotation_.~RepeatedPtrField();
 }
-void GeneratedCodeInfo::SetCachedSize(int size) const {
-  _impl_._cached_size_.Set(size);
-}
 
 PROTOBUF_NOINLINE void GeneratedCodeInfo::Clear() {
 // @@protoc_insertion_point(message_clear_start:google.protobuf.GeneratedCodeInfo)
@@ -13596,6 +13593,9 @@ PROTOBUF_NOINLINE bool GeneratedCodeInfo::IsInitialized() const {
   return true;
 }
 
+::_pbi::CachedSize* GeneratedCodeInfo::AccessCachedSize() const {
+  return &_impl_._cached_size_;
+}
 void GeneratedCodeInfo::InternalSwap(GeneratedCodeInfo* other) {
   using std::swap;
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
diff --git a/src/google/protobuf/descriptor.pb.h b/src/google/protobuf/descriptor.pb.h
index f0fc9c04d7..65e54e6da9 100644
--- a/src/google/protobuf/descriptor.pb.h
+++ b/src/google/protobuf/descriptor.pb.h
@@ -747,12 +747,12 @@ class PROTOBUF_EXPORT UninterpretedOption_NamePart final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(UninterpretedOption_NamePart* other);
 
   private:
@@ -935,12 +935,12 @@ class PROTOBUF_EXPORT SourceCodeInfo_Location final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(SourceCodeInfo_Location* other);
 
   private:
@@ -1201,12 +1201,12 @@ class PROTOBUF_EXPORT GeneratedCodeInfo_Annotation final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(GeneratedCodeInfo_Annotation* other);
 
   private:
@@ -1457,12 +1457,12 @@ class PROTOBUF_EXPORT FieldOptions_EditionDefault final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FieldOptions_EditionDefault* other);
 
   private:
@@ -1651,12 +1651,12 @@ class PROTOBUF_EXPORT FeatureSet final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FeatureSet* other);
 
   private:
@@ -2131,12 +2131,12 @@ class PROTOBUF_EXPORT ExtensionRangeOptions_Declaration final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(ExtensionRangeOptions_Declaration* other);
 
   private:
@@ -2364,12 +2364,12 @@ class PROTOBUF_EXPORT EnumDescriptorProto_EnumReservedRange final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(EnumDescriptorProto_EnumReservedRange* other);
 
   private:
@@ -2546,12 +2546,12 @@ class PROTOBUF_EXPORT DescriptorProto_ReservedRange final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(DescriptorProto_ReservedRange* other);
 
   private:
@@ -2728,12 +2728,12 @@ class PROTOBUF_EXPORT UninterpretedOption final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(UninterpretedOption* other);
 
   private:
@@ -3002,12 +3002,12 @@ class PROTOBUF_EXPORT SourceCodeInfo final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(SourceCodeInfo* other);
 
   private:
@@ -3179,12 +3179,12 @@ class PROTOBUF_EXPORT GeneratedCodeInfo final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(GeneratedCodeInfo* other);
 
   private:
@@ -3356,12 +3356,12 @@ class PROTOBUF_EXPORT FeatureSetDefaults_FeatureSetEditionDefault final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FeatureSetDefaults_FeatureSetEditionDefault* other);
 
   private:
@@ -3548,12 +3548,12 @@ class PROTOBUF_EXPORT ServiceOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(ServiceOptions* other);
 
   private:
@@ -3907,12 +3907,12 @@ class PROTOBUF_EXPORT OneofOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(OneofOptions* other);
 
   private:
@@ -4253,12 +4253,12 @@ class PROTOBUF_EXPORT MethodOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(MethodOptions* other);
 
   private:
@@ -4646,12 +4646,12 @@ class PROTOBUF_EXPORT MessageOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(MessageOptions* other);
 
   private:
@@ -5057,12 +5057,12 @@ class PROTOBUF_EXPORT FileOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FileOptions* other);
 
   private:
@@ -5744,12 +5744,12 @@ class PROTOBUF_EXPORT FieldOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FieldOptions* other);
 
   private:
@@ -6341,12 +6341,12 @@ class PROTOBUF_EXPORT FeatureSetDefaults final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FeatureSetDefaults* other);
 
   private:
@@ -6557,12 +6557,12 @@ class PROTOBUF_EXPORT ExtensionRangeOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(ExtensionRangeOptions* other);
 
   private:
@@ -6958,12 +6958,12 @@ class PROTOBUF_EXPORT EnumValueOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(EnumValueOptions* other);
 
   private:
@@ -7330,12 +7330,12 @@ class PROTOBUF_EXPORT EnumOptions final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(EnumOptions* other);
 
   private:
@@ -7715,12 +7715,12 @@ class PROTOBUF_EXPORT OneofDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(OneofDescriptorProto* other);
 
   private:
@@ -7907,12 +7907,12 @@ class PROTOBUF_EXPORT MethodDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(MethodDescriptorProto* other);
 
   private:
@@ -8163,12 +8163,12 @@ class PROTOBUF_EXPORT FieldDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FieldDescriptorProto* other);
 
   private:
@@ -8553,12 +8553,12 @@ class PROTOBUF_EXPORT EnumValueDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(EnumValueDescriptorProto* other);
 
   private:
@@ -8758,12 +8758,12 @@ class PROTOBUF_EXPORT DescriptorProto_ExtensionRange final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(DescriptorProto_ExtensionRange* other);
 
   private:
@@ -8957,12 +8957,12 @@ class PROTOBUF_EXPORT ServiceDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(ServiceDescriptorProto* other);
 
   private:
@@ -9169,12 +9169,12 @@ class PROTOBUF_EXPORT EnumDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(EnumDescriptorProto* other);
 
   private:
@@ -9433,12 +9433,12 @@ class PROTOBUF_EXPORT DescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(DescriptorProto* other);
 
   private:
@@ -9798,12 +9798,12 @@ class PROTOBUF_EXPORT FileDescriptorProto final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FileDescriptorProto* other);
 
   private:
@@ -10214,12 +10214,12 @@ class PROTOBUF_EXPORT FileDescriptorSet final :
   const char* _InternalParse(const char* ptr, ::google::protobuf::internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(
       ::uint8_t* target, ::google::protobuf::io::EpsCopyOutputStream* stream) const final;
-  int GetCachedSize() const final { return _impl_._cached_size_.Get(); }
+  int GetCachedSize() const { return _impl_._cached_size_.Get(); }
 
   private:
+  ::google::protobuf::internal::CachedSize* AccessCachedSize() const final;
   void SharedCtor(::google::protobuf::Arena* arena);
   void SharedDtor();
-  void SetCachedSize(int size) const final;
   void InternalSwap(FileDescriptorSet* other);
 
   private:
diff --git a/src/google/protobuf/dynamic_message.cc b/src/google/protobuf/dynamic_message.cc
index 15ba89876f..3edd940963 100644
--- a/src/google/protobuf/dynamic_message.cc
+++ b/src/google/protobuf/dynamic_message.cc
@@ -227,8 +227,9 @@ class DynamicMessage final : public Message {
 
   Message* New(Arena* arena) const override;
 
-  int GetCachedSize() const override;
-  void SetCachedSize(int size) const override;
+  internal::CachedSize* AccessCachedSize() const final {
+    return &cached_byte_size_;
+  }
 
   Metadata GetMetadata() const override;
 
@@ -270,7 +271,7 @@ class DynamicMessage final : public Message {
   void* MutableOneofFieldRaw(const FieldDescriptor* f);
 
   const DynamicMessageFactory::TypeInfo* type_info_;
-  mutable std::atomic<int> cached_byte_size_;
+  mutable internal::CachedSize cached_byte_size_;
 };
 
 struct DynamicMessageFactory::TypeInfo {
@@ -613,14 +614,6 @@ Message* DynamicMessage::New(Arena* arena) const {
   }
 }
 
-int DynamicMessage::GetCachedSize() const {
-  return cached_byte_size_.load(std::memory_order_relaxed);
-}
-
-void DynamicMessage::SetCachedSize(int size) const {
-  cached_byte_size_.store(size, std::memory_order_relaxed);
-}
-
 Metadata DynamicMessage::GetMetadata() const {
   Metadata metadata;
   metadata.descriptor = type_info_->type;
diff --git a/src/google/protobuf/generated_message_bases.h b/src/google/protobuf/generated_message_bases.h
index 23798cc4c7..24d94ae2d0 100644
--- a/src/google/protobuf/generated_message_bases.h
+++ b/src/google/protobuf/generated_message_bases.h
@@ -55,21 +55,23 @@ class PROTOBUF_EXPORT ZeroFieldsBase : public Message {
   PROTOBUF_ATTRIBUTE_REINITIALIZES void Clear() final;
   bool IsInitialized() const final { return true; }
   size_t ByteSizeLong() const final;
-  int GetCachedSize() const final { return _cached_size_.Get(); }
+  int GetCachedSize() const { return _cached_size_.Get(); }
   const char* _InternalParse(const char* ptr,
                              internal::ParseContext* ctx) final;
   ::uint8_t* _InternalSerialize(::uint8_t* target,
                                 io::EpsCopyOutputStream* stream) const final;
 
  protected:
+  internal::CachedSize* AccessCachedSize() const final {
+    return &_cached_size_;
+  }
+
   constexpr ZeroFieldsBase() {}
   explicit ZeroFieldsBase(Arena* arena) : Message(arena) {}
   ZeroFieldsBase(const ZeroFieldsBase&) = delete;
   ZeroFieldsBase& operator=(const ZeroFieldsBase&) = delete;
   ~ZeroFieldsBase() override;
 
-  void SetCachedSize(int size) const final { _cached_size_.Set(size); }
-
   static void MergeImpl(Message& to, const Message& from);
   static void CopyImpl(Message& to, const Message& from);
   void InternalSwap(ZeroFieldsBase* other);
diff --git a/src/google/protobuf/generated_message_util.h b/src/google/protobuf/generated_message_util.h
index 8e7f48a924..01fad5fb46 100644
--- a/src/google/protobuf/generated_message_util.h
+++ b/src/google/protobuf/generated_message_util.h
@@ -192,62 +192,6 @@ T* GetOwnedMessage(Arena* message_arena, T* submessage,
       submessage_arena));
 }
 
-// Hide atomic from the public header and allow easy change to regular int
-// on platforms where the atomic might have a perf impact.
-//
-// CachedSize is like std::atomic<int> but with some important changes:
-//
-// 1) CachedSize uses Get / Set rather than load / store.
-// 2) CachedSize always uses relaxed ordering.
-// 3) CachedSize is assignable and copy-constructible.
-// 4) CachedSize has a constexpr default constructor, and a constexpr
-//    constructor that takes an int argument.
-// 5) If the compiler supports the __atomic_load_n / __atomic_store_n builtins,
-//    then CachedSize is trivially copyable.
-//
-// Developed at https://godbolt.org/z/vYcx7zYs1 ; supports gcc, clang, MSVC.
-class PROTOBUF_EXPORT CachedSize {
- private:
-  using Scalar = int;
-
- public:
-  constexpr CachedSize() noexcept : atom_(Scalar{}) {}
-  // NOLINTNEXTLINE(google-explicit-constructor)
-  constexpr CachedSize(Scalar desired) noexcept : atom_(desired) {}
-#if PROTOBUF_BUILTIN_ATOMIC
-  constexpr CachedSize(const CachedSize& other) = default;
-
-  Scalar Get() const noexcept {
-    return __atomic_load_n(&atom_, __ATOMIC_RELAXED);
-  }
-
-  void Set(Scalar desired) noexcept {
-    __atomic_store_n(&atom_, desired, __ATOMIC_RELAXED);
-  }
-#else
-  CachedSize(const CachedSize& other) noexcept : atom_(other.Get()) {}
-  CachedSize& operator=(const CachedSize& other) noexcept {
-    Set(other.Get());
-    return *this;
-  }
-
-  Scalar Get() const noexcept {  //
-    return atom_.load(std::memory_order_relaxed);
-  }
-
-  void Set(Scalar desired) noexcept {
-    atom_.store(desired, std::memory_order_relaxed);
-  }
-#endif
-
- private:
-#if PROTOBUF_BUILTIN_ATOMIC
-  Scalar atom_;
-#else
-  std::atomic<Scalar> atom_;
-#endif
-};
-
 PROTOBUF_EXPORT void DestroyMessage(const void* message);
 PROTOBUF_EXPORT void DestroyString(const void* s);
 // Destroy (not delete) the message
diff --git a/src/google/protobuf/implicit_weak_message.h b/src/google/protobuf/implicit_weak_message.h
index b9ff1fa28d..a17cbd43c2 100644
--- a/src/google/protobuf/implicit_weak_message.h
+++ b/src/google/protobuf/implicit_weak_message.h
@@ -112,10 +112,6 @@ class PROTOBUF_EXPORT ImplicitWeakMessage : public MessageLite {
                             target);
   }
 
-  int GetCachedSize() const override {
-    return data_ == nullptr ? 0 : static_cast<int>(data_->size());
-  }
-
   typedef void InternalArenaConstructable_;
 
  private:
diff --git a/src/google/protobuf/map_entry.h b/src/google/protobuf/map_entry.h
index a51bc4ecf1..62903aae52 100644
--- a/src/google/protobuf/map_entry.h
+++ b/src/google/protobuf/map_entry.h
@@ -226,8 +226,6 @@ class MapEntry : public Message {
     return ValueTypeHandler::Write(kValueFieldNumber, value(), ptr, stream);
   }
 
-  int GetCachedSize() const override { return ByteSizeLong(); }
-
   bool IsInitialized() const override {
     return ValueTypeHandler::IsInitialized(value_);
   }
diff --git a/src/google/protobuf/message.cc b/src/google/protobuf/message.cc
index 94cad748dd..aeded53cd1 100644
--- a/src/google/protobuf/message.cc
+++ b/src/google/protobuf/message.cc
@@ -179,14 +179,15 @@ uint8_t* Message::_InternalSerialize(uint8_t* target,
 
 size_t Message::ByteSizeLong() const {
   size_t size = WireFormat::ByteSize(*this);
-  SetCachedSize(internal::ToCachedSize(size));
-  return size;
-}
 
-void Message::SetCachedSize(int /* size */) const {
-  ABSL_LOG(FATAL) << "Message class \"" << GetDescriptor()->full_name()
-                  << "\" implements neither SetCachedSize() nor ByteSize().  "
-                     "Must implement one or the other.";
+  auto* cached_size = AccessCachedSize();
+  ABSL_CHECK(cached_size != nullptr)
+      << "Message class \"" << GetDescriptor()->full_name()
+      << "\" implements neither AccessCachedSize() nor ByteSizeLong().  "
+         "Must implement one or the other.";
+  cached_size->Set(internal::ToCachedSize(size));
+
+  return size;
 }
 
 size_t Message::ComputeUnknownFieldsSize(
diff --git a/src/google/protobuf/message.h b/src/google/protobuf/message.h
index d671cfcf93..df4ef42571 100644
--- a/src/google/protobuf/message.h
+++ b/src/google/protobuf/message.h
@@ -366,17 +366,6 @@ class PROTOBUF_EXPORT Message : public MessageLite {
   uint8_t* _InternalSerialize(uint8_t* target,
                               io::EpsCopyOutputStream* stream) const override;
 
- private:
-  // This is called only by the default implementation of ByteSize(), to
-  // update the cached size.  If you override ByteSize(), you do not need
-  // to override this.  If you do not override ByteSize(), you MUST override
-  // this; the default implementation will crash.
-  //
-  // The method is private because subclasses should never call it; only
-  // override it.  Yes, C++ lets you do that.  Crazy, huh?
-  virtual void SetCachedSize(int size) const;
-
- public:
   // Introspection ---------------------------------------------------
 
 
diff --git a/src/google/protobuf/message_lite.cc b/src/google/protobuf/message_lite.cc
index 1ea4d02843..bd871e3ffc 100644
--- a/src/google/protobuf/message_lite.cc
+++ b/src/google/protobuf/message_lite.cc
@@ -75,6 +75,14 @@ std::string MessageLite::DebugString() const {
   return absl::StrCat("MessageLite at 0x", absl::Hex(this));
 }
 
+int MessageLite::GetCachedSize() const {
+  auto* cached_size = AccessCachedSize();
+  if (PROTOBUF_PREDICT_FALSE(cached_size == nullptr)) return ByteSize();
+  return cached_size->Get();
+}
+
+internal::CachedSize* MessageLite::AccessCachedSize() const { return nullptr; }
+
 namespace {
 
 // When serializing, we first compute the byte size, then serialize the message.
diff --git a/src/google/protobuf/message_lite.h b/src/google/protobuf/message_lite.h
index 4fcb6e6ec4..4dc7fb00ee 100644
--- a/src/google/protobuf/message_lite.h
+++ b/src/google/protobuf/message_lite.h
@@ -39,6 +39,7 @@
 #ifndef GOOGLE_PROTOBUF_MESSAGE_LITE_H__
 #define GOOGLE_PROTOBUF_MESSAGE_LITE_H__
 
+#include <atomic>
 #include <climits>
 #include <iosfwd>
 #include <string>
@@ -84,6 +85,62 @@ class ZeroCopyOutputStream;
 }  // namespace io
 namespace internal {
 
+// Allow easy change to regular int on platforms where the atomic might have a
+// perf impact.
+//
+// CachedSize is like std::atomic<int> but with some important changes:
+//
+// 1) CachedSize uses Get / Set rather than load / store.
+// 2) CachedSize always uses relaxed ordering.
+// 3) CachedSize is assignable and copy-constructible.
+// 4) CachedSize has a constexpr default constructor, and a constexpr
+//    constructor that takes an int argument.
+// 5) If the compiler supports the __atomic_load_n / __atomic_store_n builtins,
+//    then CachedSize is trivially copyable.
+//
+// Developed at https://godbolt.org/z/vYcx7zYs1 ; supports gcc, clang, MSVC.
+class PROTOBUF_EXPORT CachedSize {
+ private:
+  using Scalar = int;
+
+ public:
+  constexpr CachedSize() noexcept : atom_(Scalar{}) {}
+  // NOLINTNEXTLINE(google-explicit-constructor)
+  constexpr CachedSize(Scalar desired) noexcept : atom_(desired) {}
+#if PROTOBUF_BUILTIN_ATOMIC
+  constexpr CachedSize(const CachedSize& other) = default;
+
+  Scalar Get() const noexcept {
+    return __atomic_load_n(&atom_, __ATOMIC_RELAXED);
+  }
+
+  void Set(Scalar desired) noexcept {
+    __atomic_store_n(&atom_, desired, __ATOMIC_RELAXED);
+  }
+#else
+  CachedSize(const CachedSize& other) noexcept : atom_(other.Get()) {}
+  CachedSize& operator=(const CachedSize& other) noexcept {
+    Set(other.Get());
+    return *this;
+  }
+
+  Scalar Get() const noexcept {  //
+    return atom_.load(std::memory_order_relaxed);
+  }
+
+  void Set(Scalar desired) noexcept {
+    atom_.store(desired, std::memory_order_relaxed);
+  }
+#endif
+
+ private:
+#if PROTOBUF_BUILTIN_ATOMIC
+  Scalar atom_;
+#else
+  std::atomic<Scalar> atom_;
+#endif
+};
+
 class SwapFieldHelper;
 
 // See parse_context.h for explanation
@@ -451,7 +508,7 @@ class PROTOBUF_EXPORT MessageLite {
   // sub-message is changed, all of its parents' cached sizes would need to be
   // invalidated, which is too much work for an otherwise inlined setter
   // method.)
-  virtual int GetCachedSize() const = 0;
+  int GetCachedSize() const;
 
   virtual const char* _InternalParse(const char* /*ptr*/,
                                      internal::ParseContext* /*ctx*/) {
@@ -493,6 +550,10 @@ class PROTOBUF_EXPORT MessageLite {
 
   internal::InternalMetadata _internal_metadata_;
 
+  // The default implementation means there is no cached size and ByteSize
+  // should be called instead.
+  virtual internal::CachedSize* AccessCachedSize() const;
+
  public:
   enum ParseFlags {
     kMerge = 0,