Index: cfe/trunk/lib/CodeGen/CGObjCMac.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGObjCMac.cpp
+++ cfe/trunk/lib/CodeGen/CGObjCMac.cpp
@@ -3401,7 +3401,9 @@
   See EmitClassExtension();
 */
 void CGObjCMac::GenerateClass(const ObjCImplementationDecl *ID) {
-  DefinedSymbols.insert(ID->getIdentifier());
+  IdentifierInfo *RuntimeName =
+      &CGM.getContext().Idents.get(ID->getObjCRuntimeNameAsString());
+  DefinedSymbols.insert(RuntimeName);
 
   std::string ClassName = ID->getNameAsString();
   // FIXME: Gross
@@ -4980,7 +4982,9 @@
   if (ID->hasAttr<ObjCRuntimeVisibleAttr>())
     return EmitClassRefViaRuntime(CGF, ID, ObjCTypes);
 
-  return EmitClassRefFromId(CGF, ID->getIdentifier());
+  IdentifierInfo *RuntimeName =
+      &CGM.getContext().Idents.get(ID->getObjCRuntimeNameAsString());
+  return EmitClassRefFromId(CGF, RuntimeName);
 }
 
 llvm::Value *CGObjCMac::EmitNSAutoreleasePoolClassRef(CodeGenFunction &CGF) {
Index: cfe/trunk/test/CodeGenObjC/objc-runtime-name.m
===================================================================
--- cfe/trunk/test/CodeGenObjC/objc-runtime-name.m
+++ cfe/trunk/test/CodeGenObjC/objc-runtime-name.m
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -triple i386-apple-macosx10.13.0 -fobjc-runtime=macosx-fragile-10.13.0 -fobjc-subscripting-legacy-runtime -emit-llvm -o - %s | FileCheck %s
+
+// Check that the runtime name is emitted and used instead of the class
+// identifier.
+
+// CHECK: module asm {{.*}}objc_class_name_XYZ=0
+// CHECK: module asm {{.*}}globl .objc_class_name_XYZ
+// CHECK: module asm {{.*}}lazy_reference .objc_class_name_XYZ
+
+// CHECK: @[[OBJC_CLASS_NAME:.*]] = private unnamed_addr constant [4 x i8] c"XYZ{{.*}}, section "__TEXT,__cstring,cstring_literals",
+// CHECK: = private global {{.*}} bitcast ([4 x i8]* @[[OBJC_CLASS_NAME]] to {{.*}}), section "__OBJC,__cls_refs,literal_pointers,no_dead_strip"
+
+__attribute__((objc_root_class,objc_runtime_name("XYZ")))
+@interface A
++(void)m1;
+@end
+
+@implementation A
++(void)m1 {}
+@end
+
+void test(void) {
+  [A m1];
+}