Index: include/llvm/Support/AlignOf.h
===================================================================
--- include/llvm/Support/AlignOf.h
+++ include/llvm/Support/AlignOf.h
@@ -103,44 +103,34 @@
 #endif // _MSC_VER
 
 namespace detail {
-template <typename T1,
-          typename T2 = char, typename T3 = char, typename T4 = char,
-          typename T5 = char, typename T6 = char, typename T7 = char,
-          typename T8 = char, typename T9 = char, typename T10 = char>
-class AlignerImpl {
-  T1 t1; T2 t2; T3 t3; T4 t4; T5 t5; T6 t6; T7 t7; T8 t8; T9 t9; T10 t10;
+template <typename... Ts> class AlignerImpl;
 
+template <typename T1, typename... Ts> class AlignerImpl<T1, Ts...> : AlignerImpl<Ts...> {
+  T1 t;
   AlignerImpl() = delete;
 };
 
-template <typename T1,
-          typename T2 = char, typename T3 = char, typename T4 = char,
-          typename T5 = char, typename T6 = char, typename T7 = char,
-          typename T8 = char, typename T9 = char, typename T10 = char>
-union SizerImpl {
-  char arr1[sizeof(T1)], arr2[sizeof(T2)], arr3[sizeof(T3)], arr4[sizeof(T4)],
-       arr5[sizeof(T5)], arr6[sizeof(T6)], arr7[sizeof(T7)], arr8[sizeof(T8)],
-       arr9[sizeof(T9)], arr10[sizeof(T10)];
+template <> class AlignerImpl<> {
+  AlignerImpl() = delete;
 };
+
+template <typename T1> constexpr size_t sizer() { return sizeof(T1); }
+
+template <typename T1, typename T2, typename... Ts> constexpr size_t sizer() {
+  return (sizeof(T1) > sizer<T2, Ts...>()) ? sizeof(T1) : sizer<T2, Ts...>();
+}
 } // end namespace detail
 
 /// \brief This union template exposes a suitably aligned and sized character
-/// array member which can hold elements of any of up to ten types.
+/// array member which can hold elements of any of a number of types.
 ///
 /// These types may be arrays, structs, or any other types. The goal is to
 /// expose a char array buffer member which can be used as suitable storage for
-/// a placement new of any of these types. Support for more than ten types can
-/// be added at the cost of more boilerplate.
-template <typename T1,
-          typename T2 = char, typename T3 = char, typename T4 = char,
-          typename T5 = char, typename T6 = char, typename T7 = char,
-          typename T8 = char, typename T9 = char, typename T10 = char>
-struct AlignedCharArrayUnion : llvm::AlignedCharArray<
-    alignof(llvm::detail::AlignerImpl<T1, T2, T3, T4, T5,
-                                      T6, T7, T8, T9, T10>),
-    sizeof(::llvm::detail::SizerImpl<T1, T2, T3, T4, T5,
-                                     T6, T7, T8, T9, T10>)> {
-};
+/// a placement new of any of these types.
+template <typename... Ts>
+struct AlignedCharArrayUnion
+    : llvm::AlignedCharArray<alignof(llvm::detail::AlignerImpl<Ts...>),
+                             detail::sizer<Ts...>()> {};
 } // end namespace llvm
 
 #endif // LLVM_SUPPORT_ALIGNOF_H
Index: unittests/ADT/AlignOfTest.cpp
===================================================================
--- unittests/ADT/AlignOfTest.cpp
+++ unittests/ADT/AlignOfTest.cpp
@@ -0,0 +1,43 @@
+//===----------- AlignOfTest.cpp - AlignOf unit tests ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/Support/AlignOf.h"
+
+using namespace llvm;
+namespace {
+
+typedef uint8_t t1;
+typedef uint16_t t2;
+typedef uint32_t t3;
+typedef uint64_t t4;
+typedef int8_t t5;
+typedef int16_t t6;
+typedef int32_t t7;
+typedef int64_t t8;
+typedef struct { uint8_t bytes[16]; } t9;
+typedef struct { uint16_t words[16]; } t10;
+typedef struct { uint32_t words[16]; } t11;
+typedef struct { uint64_t words[16]; } t12;
+
+typedef AlignedCharArrayUnion<t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12> U;
+
+struct static_tests {
+  static_assert(sizeof(U) == sizeof(uint64_t[16]), "Statically-computed size must be right");
+  static_assert(alignof(U) == alignof(uint64_t), "Statically-computed alignment must be right");
+};
+
+TEST(AlignOf, BufferCanBeUsed) {
+  U MyU;
+  memset(MyU.buffer, 'X', sizeof(U));
+  
+  EXPECT_EQ(MyU.buffer[sizeof(uint64_t[16]) - 1], 'X');
+}
+
+}  // namespace
Index: unittests/ADT/CMakeLists.txt
===================================================================
--- unittests/ADT/CMakeLists.txt
+++ unittests/ADT/CMakeLists.txt
@@ -3,6 +3,7 @@
   )
 
 set(ADTSources
+  AlignOfTest.cpp
   APFloatTest.cpp
   APIntTest.cpp
   APSIntTest.cpp