Index: cfe/trunk/lib/Basic/Targets.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets.cpp
+++ cfe/trunk/lib/Basic/Targets.cpp
@@ -3629,13 +3629,21 @@
     LongDoubleWidth = 128;
     LongDoubleAlign = 128;
     SuitableAlign = 128;
-    MaxVectorAlign = 256;
     SizeType = UnsignedLong;
     IntPtrType = SignedLong;
     DataLayoutString = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128";
     HasAlignMac68kSupport = true;
   }
 
+  bool handleTargetFeatures(std::vector<std::string> &Features,
+                            DiagnosticsEngine &Diags) override {
+    if (!DarwinTargetInfo<X86_32TargetInfo>::handleTargetFeatures(Features,
+                                                                  Diags))
+      return false;
+    // Now that we know if we have AVX, we can decide how to align vectors.
+    MaxVectorAlign = hasFeature("avx") ? 256 : 128;
+    return true;
+  }
 };
 
 // x86-32 Windows target
@@ -3986,13 +3994,22 @@
   DarwinX86_64TargetInfo(const llvm::Triple &Triple)
       : DarwinTargetInfo<X86_64TargetInfo>(Triple) {
     Int64Type = SignedLongLong;
-    MaxVectorAlign = 256;
     // The 64-bit iOS simulator uses the builtin bool type for Objective-C.
     llvm::Triple T = llvm::Triple(Triple);
     if (T.isiOS())
       UseSignedCharForObjCBool = false;
     DataLayoutString = "e-m:o-i64:64-f80:128-n8:16:32:64-S128";
   }
+
+  bool handleTargetFeatures(std::vector<std::string> &Features,
+                            DiagnosticsEngine &Diags) override {
+    if (!DarwinTargetInfo<X86_64TargetInfo>::handleTargetFeatures(Features,
+                                                                  Diags))
+      return false;
+    // Now that we know if we have AVX, we can decide how to align vectors.
+    MaxVectorAlign = hasFeature("avx") ? 256 : 128;
+    return true;
+  }
 };
 
 class OpenBSDX86_64TargetInfo : public OpenBSDTargetInfo<X86_64TargetInfo> {
Index: cfe/trunk/test/CodeGen/vector-alignment.c
===================================================================
--- cfe/trunk/test/CodeGen/vector-alignment.c
+++ cfe/trunk/test/CodeGen/vector-alignment.c
@@ -1,38 +1,51 @@
-// RUN: %clang_cc1 -w -triple x86_64-apple-darwin10 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -w -triple x86_64-apple-darwin10 \
+// RUN:  -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL --check-prefix=SSE
+// RUN: %clang_cc1 -w -triple   i386-apple-darwin10 \
+// RUN:  -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL --check-prefix=SSE
+// RUN: %clang_cc1 -w -triple x86_64-apple-darwin10 -target-feature +avx \
+// RUN:  -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL --check-prefix=AVX
+// RUN: %clang_cc1 -w -triple   i386-apple-darwin10 -target-feature +avx \
+// RUN:  -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL --check-prefix=AVX
 // rdar://11759609
 
 // At or below target max alignment with no aligned attribute should align based
 // on the size of vector.
 double __attribute__((vector_size(16))) v1;
-// CHECK: @v1 {{.*}}, align 16
+// SSE: @v1 {{.*}}, align 16
+// AVX: @v1 {{.*}}, align 16
 double __attribute__((vector_size(32))) v2;
-// CHECK: @v2 {{.*}}, align 32
+// SSE: @v2 {{.*}}, align 16
+// AVX: @v2 {{.*}}, align 32
 
 // Alignment above target max alignment with no aligned attribute should align
 // based on the target max.
 double __attribute__((vector_size(64))) v3;
-// CHECK: @v3 {{.*}}, align 32
+// SSE: @v3 {{.*}}, align 16
+// AVX: @v3 {{.*}}, align 32
 double __attribute__((vector_size(1024))) v4;
-// CHECK: @v4 {{.*}}, align 32
+// SSE: @v4 {{.*}}, align 16
+// AVX: @v4 {{.*}}, align 32
 
 // Aliged attribute should always override.
 double __attribute__((vector_size(16), aligned(16))) v5;
-// CHECK: @v5 {{.*}}, align 16
+// ALL: @v5 {{.*}}, align 16
 double __attribute__((vector_size(16), aligned(64))) v6;
-// CHECK: @v6 {{.*}}, align 64
+// ALL: @v6 {{.*}}, align 64
 double __attribute__((vector_size(32), aligned(16))) v7;
-// CHECK: @v7 {{.*}}, align 16
+// ALL: @v7 {{.*}}, align 16
 double __attribute__((vector_size(32), aligned(64))) v8;
-// CHECK: @v8 {{.*}}, align 64
+// ALL: @v8 {{.*}}, align 64
 
 // Check non-power of 2 widths.
 double __attribute__((vector_size(24))) v9;
-// CHECK: @v9 {{.*}}, align 32
+// SSE: @v9 {{.*}}, align 16
+// AVX: @v9 {{.*}}, align 32
 double __attribute__((vector_size(40))) v10;
-// CHECK: @v10 {{.*}}, align 32
+// SSE: @v10 {{.*}}, align 16
+// AVX: @v10 {{.*}}, align 32
 
 // Check non-power of 2 widths with aligned attribute.
 double __attribute__((vector_size(24), aligned(64))) v11;
-// CHECK: @v11 {{.*}}, align 64
+// ALL: @v11 {{.*}}, align 64
 double __attribute__((vector_size(80), aligned(16))) v12;
-// CHECK: @v12 {{.*}}, align 16
+// ALL: @v12 {{.*}}, align 16