Index: include/clang/Basic/TargetInfo.h
===================================================================
--- include/clang/Basic/TargetInfo.h
+++ include/clang/Basic/TargetInfo.h
@@ -72,7 +72,7 @@
   unsigned char LargeArrayMinWidth, LargeArrayAlign;
   unsigned char LongWidth, LongAlign;
   unsigned char LongLongWidth, LongLongAlign;
-  unsigned char SuitableAlign;
+  unsigned short SuitableAlign;
   unsigned char DefaultAlignForAttributeAligned;
   unsigned char MinGlobalAlign;
   unsigned char MaxAtomicPromoteWidth, MaxAtomicInlineWidth;
Index: lib/Basic/Targets/X86.cpp
===================================================================
--- lib/Basic/Targets/X86.cpp
+++ lib/Basic/Targets/X86.cpp
@@ -747,7 +747,7 @@
     return false;
   }
 
-  SimdDefaultAlign =
+  SuitableAlign = SimdDefaultAlign =
       hasFeature("avx512f") ? 512 : hasFeature("avx") ? 256 : 128;
   return true;
 }
Index: test/CodeGen/builtins-alloca.c
===================================================================
--- /dev/null
+++ test/CodeGen/builtins-alloca.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | \
+// RUN:   FileCheck %s -check-prefix=CHECK_X86_64
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx | \
+// RUN:   FileCheck %s -check-prefix=CHECK_X86_64_AVX
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx512f | \
+// RUN:   FileCheck %s -check-prefix=CHECK_X86_64_AVX512
+
+
+char *c1; 
+// CHECK_X86_64: %1 = alloca i8, i64 1, align 16
+// CHECK_X86_64_AVX: %1 = alloca i8, i64 1, align 32
+// CHECK_X86_64_AVX512: %1 = alloca i8, i64 1, align 64
+void f1() {
+    c1 = __builtin_alloca(1);
+}