Index: lib/Basic/Targets/AMDGPU.cpp
===================================================================
--- lib/Basic/Targets/AMDGPU.cpp
+++ lib/Basic/Targets/AMDGPU.cpp
@@ -260,6 +260,10 @@
   }
 
   MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
+#if _WIN32
+  WCharType = UnsignedShort;
+  WIntType = UnsignedShort;
+#endif
 }
 
 void AMDGPUTargetInfo::adjust(LangOptions &Opts) {
Index: test/SemaCXX/amdgpu-wchar.cxx
===================================================================
--- /dev/null
+++ test/SemaCXX/amdgpu-wchar.cxx
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple amdgcn -std=c++11 %s
+
+typedef __WINT_TYPE__ wint_t;
+
+#if _WIN32
+static_assert(sizeof(wchar_t)==2, "fail");
+static_assert(sizeof(wint_t)==2, "fail");
+#else
+static_assert(sizeof(wchar_t)==4, "fail");
+static_assert(sizeof(wint_t)==4, "fail");
+#endif