diff --git a/lib/IRGen/GenReflection.cpp b/lib/IRGen/GenReflection.cpp
index d645a3f95419e..4d14591f859b8 100644
--- a/lib/IRGen/GenReflection.cpp
+++ b/lib/IRGen/GenReflection.cpp
@@ -1630,26 +1630,33 @@ emitAssociatedTypeMetadataRecord(const RootProtocolConformance *conformance) {
   builder.emit();
 }
 
-void IRGenModule::emitBuiltinReflectionMetadata() {
-  if (getSwiftModule()->isStdlibModule()) {
-    BuiltinTypes.insert(Context.TheNativeObjectType);
-    BuiltinTypes.insert(Context.getAnyObjectType());
-    BuiltinTypes.insert(Context.TheBridgeObjectType);
-    BuiltinTypes.insert(Context.TheRawPointerType);
-    BuiltinTypes.insert(Context.TheUnsafeValueBufferType);
+llvm::ArrayRef<CanType> IRGenModule::getOrCreateSpecialStlibBuiltinTypes() {
+  if (SpecialStdlibBuiltinTypes.empty()) {
+    SpecialStdlibBuiltinTypes.push_back(Context.TheNativeObjectType);
+    SpecialStdlibBuiltinTypes.push_back(Context.getAnyObjectType());
+    SpecialStdlibBuiltinTypes.push_back(Context.TheBridgeObjectType);
+    SpecialStdlibBuiltinTypes.push_back(Context.TheRawPointerType);
+    SpecialStdlibBuiltinTypes.push_back(Context.TheUnsafeValueBufferType);
 
     // This would not be necessary if RawPointer had the same set of
     // extra inhabitants as these. But maybe it's best not to codify
     // that in the ABI anyway.
-    CanType thinFunction = CanFunctionType::get(
-      {}, Context.TheEmptyTupleType,
-      AnyFunctionType::ExtInfo().withRepresentation(
-          FunctionTypeRepresentation::Thin));
-    BuiltinTypes.insert(thinFunction);
-
-    CanType anyMetatype = CanExistentialMetatypeType::get(
-      Context.TheAnyType);
-    BuiltinTypes.insert(anyMetatype);
+    CanType thinFunction =
+        CanFunctionType::get({}, Context.TheEmptyTupleType,
+                             AnyFunctionType::ExtInfo().withRepresentation(
+                                 FunctionTypeRepresentation::Thin));
+    SpecialStdlibBuiltinTypes.push_back(thinFunction);
+
+    CanType anyMetatype = CanExistentialMetatypeType::get(Context.TheAnyType);
+    SpecialStdlibBuiltinTypes.push_back(anyMetatype);
+  }
+  return SpecialStdlibBuiltinTypes;
+}
+
+void IRGenModule::emitBuiltinReflectionMetadata() {
+  if (getSwiftModule()->isStdlibModule()) {
+    auto SpecialBuiltins = getOrCreateSpecialStlibBuiltinTypes();
+    BuiltinTypes.insert(SpecialBuiltins.begin(), SpecialBuiltins.end());
   }
 
   for (auto builtinType : BuiltinTypes)
diff --git a/lib/IRGen/IRGenModule.h b/lib/IRGen/IRGenModule.h
index 708c6585ab33a..45db78ea3acda 100644
--- a/lib/IRGen/IRGenModule.h
+++ b/lib/IRGen/IRGenModule.h
@@ -1430,6 +1430,14 @@ class IRGenModule {
   const char *getReflectionTypeRefSectionName();
   const char *getMultiPayloadEnumDescriptorSectionName();
 
+  /// Returns the special builtin types that should be emitted in the stdlib
+  /// module.
+  llvm::ArrayRef<CanType> getOrCreateSpecialStlibBuiltinTypes();
+
+private:
+  /// The special builtin types that should be emitted in the stdlib module.
+  llvm::SmallVector<CanType, 7> SpecialStdlibBuiltinTypes;
+
 //--- Runtime ---------------------------------------------------------------
 public:
   llvm::Constant *getEmptyTupleMetadata();