diff --git a/lib/Target/X86/X86CallingConv.td b/lib/Target/X86/X86CallingConv.td
index 3206e18..d4f4e26 100644
--- a/lib/Target/X86/X86CallingConv.td
+++ b/lib/Target/X86/X86CallingConv.td
@@ -101,8 +101,7 @@
 // This is the root return-value convention for the X86-64 backend.
 def RetCC_X86_64 : CallingConv<[
   // Mingw64 and native Win64 use Win64 CC
-  CCIfSubtarget<"isTargetMingw()", CCDelegateTo<RetCC_X86_Win64_C>>,
-  CCIfSubtarget<"isTargetWindows()", CCDelegateTo<RetCC_X86_Win64_C>>,
+  CCIfSubtarget<"isTargetWin64()", CCDelegateTo<RetCC_X86_Win64_C>>,
 
   // Otherwise, drop to normal X86-64 CC
   CCDelegateTo<RetCC_X86_64_C>
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 933c33e..dd2d784 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1009,7 +1009,7 @@
   unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
   
   if (Subtarget->is64Bit()) {
-    if (Subtarget->isTargetWindows() || Subtarget->isTargetMingw())
+    if (Subtarget->isTargetWin64())
       return CC_X86_Win64_C;
     else {
       if (CC == CallingConv::Fast && PerformTailCallOpt)
diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index e34d1f1..6488d47 100644
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -138,6 +138,9 @@
   bool isTargetCygMing() const { return (TargetType == isMingw ||
                                          TargetType == isCygwin); }
   bool isTargetCygwin() const { return TargetType == isCygwin; }
+  bool isTargetWin64() const {
+    return (Is64Bit && (TargetType == isMingw || TargetType == isWindows));
+  }
 
   std::string getDataLayout() const {
     const char *p;