Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -4959,6 +4959,19 @@
   BuiltinVaListKind getBuiltinVaListKind() const override {
     return TargetInfo::CharPtrBuiltinVaList;
   }
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_X86StdCall:
+    case CC_X86ThisCall:
+    case CC_X86FastCall:
+    case CC_X86VectorCall:
+      return CCCR_Ignore;
+    case CC_C:
+      return CCCR_OK;
+    default:
+      return CCCR_Warning;
+    }
+  }
 };
 
 // Windows ARM + Itanium C++ ABI Target
Index: test/Parser/arm-windows-calling-convention-handling.c
===================================================================
--- test/Parser/arm-windows-calling-convention-handling.c
+++ /dev/null
@@ -1,10 +0,0 @@
-// RUN: %clang_cc1 -triple thumbv7-windows -fms-compatibility -fsyntax-only -verify %s
-
-int __cdecl cdecl(int a, int b, int c, int d) { // expected-warning {{calling convention '__cdecl' ignored for this target}}
-  return a + b + c + d;
-}
-
-float __stdcall stdcall(float a, float b, float c, float d) { // expected-warning {{calling convention '__stdcall' ignored for this target}}
-  return a + b + c + d;
-}
-