diff --git a/include/llvm/Support/AlignOf.h b/include/llvm/Support/AlignOf.h
index cf7125173ee..8c389afa80d 100644
--- a/include/llvm/Support/AlignOf.h
+++ b/include/llvm/Support/AlignOf.h
@@ -72,6 +72,10 @@ template <size_t Alignment> struct AlignedCharArrayImpl {};
 template <> struct AlignedCharArrayImpl<0> {
   typedef char type;
 };
+
+// MSVC requires special handling here.
+#ifndef _MSC_VER
+
 #if __has_feature(cxx_alignas)
 #define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \
   template <> struct AlignedCharArrayImpl<x> { \
@@ -82,11 +86,6 @@ template <> struct AlignedCharArrayImpl<0> {
   template <> struct AlignedCharArrayImpl<x> { \
     typedef char type __attribute__((aligned(x))); \
   }
-#elif defined(_MSC_VER)
-#define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \
-  template <> struct AlignedCharArrayImpl<x> { \
-    typedef __declspec(align(x)) char type; \
-  }
 #else
 # error No supported align as directive.
 #endif
@@ -104,9 +103,38 @@ LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(1024);
 LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(2048);
 LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(4096);
 LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8192);
+
+#undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT
+
+#else // _MSC_VER
+
+// We provide special variations of this template for the most common
+// alignments because __declspec(align(...)) doesn't actually work when it is
+// a member of a by-value function argument in MSVC, even if the alignment
+// request is something reasonably like 8-byte or 16-byte.
+template <> struct AlignedCharArrayImpl<1> { typedef char type; };
+template <> struct AlignedCharArrayImpl<2> { typedef short type; };
+template <> struct AlignedCharArrayImpl<4> { typedef int type; };
+template <> struct AlignedCharArrayImpl<8> { typedef double type; };
+
+#define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \
+  template <> struct AlignedCharArrayImpl<x> { \
+    typedef __declspec(align(x)) char type; \
+  }
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(16);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(32);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(64);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(512);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(1024);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(2048);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(4096);
+LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8192);
 // Any larger and MSVC complains.
 #undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT
 
+#endif // _MSC_VER
+
 /// \brief This union template exposes a suitably aligned and sized character
 /// array member which can hold elements of any of up to four types.
 ///