Index: llvm/trunk/include/llvm/Support/Endian.h
===================================================================
--- llvm/trunk/include/llvm/Support/Endian.h
+++ llvm/trunk/include/llvm/Support/Endian.h
@@ -205,7 +205,8 @@
 
 template<typename ValueType,
          endianness Endian,
-         std::size_t Alignment>
+         std::size_t Alignment,
+         std::size_t ALIGN = PickAlignment<ValueType, Alignment>::value>
 struct packed_endian_specific_integral {
   using value_type = ValueType;
   static constexpr endianness endian = Endian;
@@ -247,8 +248,7 @@
 
 private:
   struct {
-    alignas(PickAlignment<value_type,
-                          alignment>::value) char buffer[sizeof(value_type)];
+    LLVM_ALIGNAS(ALIGN) char buffer[sizeof(value_type)];
   } Value;
 
 public: