diff --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
index aa66a4ea52a4..fb6ae5dee374 100644
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -389,7 +389,8 @@
 
 /// \macro LLVM_STATIC_ASSERT
 /// \brief Expands to C/C++'s static_assert on compilers which support it.
-#if __has_feature(cxx_static_assert) || LLVM_MSC_PREREQ(1600)
+#if __has_feature(cxx_static_assert) || \
+    defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1600)
 # define LLVM_STATIC_ASSERT(expr, msg) static_assert(expr, msg)
 #elif __has_feature(c_static_assert)
 # define LLVM_STATIC_ASSERT(expr, msg) _Static_assert(expr, msg)
diff --git a/llvm/lib/Support/ThreadLocal.cpp b/llvm/lib/Support/ThreadLocal.cpp
index 868b6ea566a9..38ab29b7ffef 100644
--- a/llvm/lib/Support/ThreadLocal.cpp
+++ b/llvm/lib/Support/ThreadLocal.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Config/config.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/ThreadLocal.h"
 
 //===----------------------------------------------------------------------===//
@@ -26,7 +27,7 @@ using namespace sys;
 ThreadLocalImpl::ThreadLocalImpl() : data() { }
 ThreadLocalImpl::~ThreadLocalImpl() { }
 void ThreadLocalImpl::setInstance(const void* d) {
-  typedef int SIZE_TOO_BIG[sizeof(d) <= sizeof(data) ? 1 : -1];
+  LLVM_STATIC_ASSERT(sizeof(d) <= sizeof(data), "size too big");
   void **pd = reinterpret_cast<void**>(&data);
   *pd = const_cast<void*>(d);
 }
@@ -50,7 +51,7 @@ namespace llvm {
 using namespace sys;
 
 ThreadLocalImpl::ThreadLocalImpl() : data() {
-  typedef int SIZE_TOO_BIG[sizeof(pthread_key_t) <= sizeof(data) ? 1 : -1];
+  LLVM_STATIC_ASSERT(sizeof(pthread_key_t) <= sizeof(data), "size too big");
   pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   int errorcode = pthread_key_create(key, NULL);
   assert(errorcode == 0);