diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 72953ce..9ed3733 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -1520,7 +1520,7 @@
   const StringLiteral *SL) {
   return (CGM.getLangOptions().NoConstantCFStrings == 0 ? 
           CGM.GetAddrOfConstantCFString(SL) :
-          CGM.GetAddrOfConstantNSString(SL));
+          CGM.GetAddrOfConstantString(SL));
 }
 
 /// Generates a message send where the super is the receiver.  This is
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 175c27b..9199f6c 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -65,7 +65,7 @@
     Types(C, M, TD, getTargetCodeGenInfo().getABIInfo(), ABI),
     TBAA(0),
     VTables(*this), Runtime(0),
-    CFConstantStringClassRef(0), NSConstantStringClassRef(0),
+    CFConstantStringClassRef(0), ConstantStringClassRef(0),
     VMContext(M.getContext()),
     NSConcreteGlobalBlockDecl(0), NSConcreteStackBlockDecl(0),
     NSConcreteGlobalBlock(0), NSConcreteStackBlock(0),
@@ -1635,7 +1635,7 @@
 }
 
 llvm::Constant *
-CodeGenModule::GetAddrOfConstantNSString(const StringLiteral *Literal) {
+CodeGenModule::GetAddrOfConstantString(const StringLiteral *Literal) {
   unsigned StringLength = 0;
   bool isUTF16 = false;
   llvm::StringMapEntry<llvm::Constant*> &Entry =
@@ -1651,16 +1651,27 @@
   llvm::Constant *Zeros[] = { Zero, Zero };
   
   // If we don't already have it, get _NSConstantStringClassReference.
-  if (!NSConstantStringClassRef) {
+  if (!ConstantStringClassRef) {
+    std::string StringClass(getLangOptions().ObjCConstantStringClass);
     const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
     Ty = llvm::ArrayType::get(Ty, 0);
-    llvm::Constant *GV = CreateRuntimeVariable(Ty, 
-                                        Features.ObjCNonFragileABI ?
-                                        "OBJC_CLASS_$_NSConstantString" :
-                                        "_NSConstantStringClassReference");
+    llvm::Constant *GV;
+    if (StringClass.empty())
+      GV = CreateRuntimeVariable(Ty, 
+                                 Features.ObjCNonFragileABI ?
+                                 "OBJC_CLASS_$_NSConstantString" :
+                                 "_NSConstantStringClassReference");
+    else {
+      std::string str;
+      if (Features.ObjCNonFragileABI)
+        str = "OBJC_CLASS_$_" + StringClass;
+      else
+        str = "_" + StringClass + "ClassReference";
+      GV = CreateRuntimeVariable(Ty, str);
+    }
     // Decay array -> ptr
-    NSConstantStringClassRef = 
-      llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
+    ConstantStringClassRef = 
+    llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
   }
   
   QualType NSTy = getContext().getNSConstantStringType();
@@ -1671,7 +1682,7 @@
   std::vector<llvm::Constant*> Fields(3);
   
   // Class pointer.
-  Fields[0] = NSConstantStringClassRef;
+  Fields[0] = ConstantStringClassRef;
   
   // String pointer.
   llvm::Constant *C = llvm::ConstantArray::get(VMContext, Entry.getKey().str());
diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 236b5b7..d050eea 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -185,9 +185,9 @@
   /// strings. This value has type int * but is actually an Obj-C class pointer.
   llvm::Constant *CFConstantStringClassRef;
 
-  /// NSConstantStringClassRef - Cached reference to the class for constant
+  /// ConstantStringClassRef - Cached reference to the class for constant
   /// strings. This value has type int * but is actually an Obj-C class pointer.
-  llvm::Constant *NSConstantStringClassRef;
+  llvm::Constant *ConstantStringClassRef;
 
   /// Lazily create the Objective-C runtime
   void createObjCRuntime();
@@ -321,9 +321,10 @@
   /// for the given string.
   llvm::Constant *GetAddrOfConstantCFString(const StringLiteral *Literal);
   
-  /// GetAddrOfConstantNSString - Return a pointer to a constant NSString object
-  /// for the given string.
-  llvm::Constant *GetAddrOfConstantNSString(const StringLiteral *Literal);
+  /// GetAddrOfConstantString - Return a pointer to a constant NSString object
+  /// for the given string. Or a user defined String object as defined via
+  /// -fconstant-string-class=class_name option.
+  llvm::Constant *GetAddrOfConstantString(const StringLiteral *Literal);
 
   /// GetAddrOfConstantStringFromLiteral - Return a pointer to a constant array
   /// for the given string literal.