Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -2183,10 +2183,16 @@
 /// Run the required checks for the extended vector type.
 QualType Sema::BuildExtVectorType(QualType T, Expr *ArraySize,
                                   SourceLocation AttrLoc) {
-  // unlike gcc's vector_size attribute, we do not allow vectors to be defined
+  // Unlike gcc's vector_size attribute, we do not allow vectors to be defined
   // in conjunction with complex types (pointers, arrays, functions, etc.).
-  if (!T->isDependentType() &&
-      !T->isIntegerType() && !T->isRealFloatingType()) {
+  //
+  // Additionally, OpenCL prohibits vectors of booleans (they're considered a
+  // reserved data type under OpenCL v2.0 s6.1.4), we don't support selects
+  // on bitvectors, and we have no well-defined ABI for bitvectors, so vectors
+  // of bool aren't allowed.
+  if ((!T->isDependentType() && !T->isIntegerType() &&
+       !T->isRealFloatingType()) ||
+      T->isBooleanType()) {
     Diag(AttrLoc, diag::err_attribute_invalid_vector_type) << T;
     return QualType();
   }
@@ -2200,7 +2206,7 @@
       return QualType();
     }
 
-    // unlike gcc's vector_size attribute, the size is specified as the
+    // Unlike gcc's vector_size attribute, the size is specified as the
     // number of elements, not the number of bytes.
     unsigned vectorSize = static_cast<unsigned>(vecSize.getZExtValue());
 
Index: test/CodeGen/convertvector.c
===================================================================
--- test/CodeGen/convertvector.c
+++ test/CodeGen/convertvector.c
@@ -9,14 +9,6 @@
 typedef unsigned short  vector8ushort  __attribute__((__vector_size__(16)));
 
 #ifdef __cplusplus
-#define BOOL bool
-#else
-#define BOOL _Bool
-#endif
-
-typedef BOOL vector8bool __attribute__((__ext_vector_type__(8)));
-
-#ifdef __cplusplus
 extern "C" {
 #endif
 
@@ -32,13 +24,6 @@
   // CHECK: fpext <8 x float> %{{[^ ]}} to <8 x double>
 }
 
-vector8bool flt_tobool(vector8float x) {
-  return __builtin_convertvector(x, vector8bool);
-  // CHECK-LABEL: @flt_tobool
-  // CHECK-NOT: fptoui <8 x float> %{{[^ ]}} to <8 x i1>
-  // CHECK: fcmp une <8 x float> %{{[^ ]}}, zeroinitializer
-}
-
 vector8long flt_tosi(vector8float x) {
   return __builtin_convertvector(x, vector8long);
   // CHECK-LABEL: @flt_tosi
@@ -69,13 +54,6 @@
   // CHECK: sext <8 x i16> %{{[^ ]}} to <8 x i64>
 }
 
-vector8bool int_tobool(vector8short x) {
-  return __builtin_convertvector(x, vector8bool);
-  // CHECK-LABEL: @int_tobool
-  // CHECK-NOT: trunc <8 x i16> %{{[^ ]}} to <8 x i1>
-  // CHECK: icmp ne <8 x i16> %{{[^ ]}}, zeroinitializer
-}
-
 vector8float int_tofp(vector8short x) {
   return __builtin_convertvector(x, vector8float);
   // CHECK-LABEL: @int_tofp
Index: test/Sema/ext_vector_casts.c
===================================================================
--- test/Sema/ext_vector_casts.c
+++ test/Sema/ext_vector_casts.c
@@ -1,5 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-apple-macos10.7.0 -fsyntax-only -verify -fno-lax-vector-conversions -Wconversion %s
 
+typedef __attribute__((ext_vector_type(8))) _Bool BoolVector; // expected-error {{invalid vector element type '_Bool'}}
+
 typedef __attribute__(( ext_vector_type(2) )) float float2;
 typedef __attribute__(( ext_vector_type(3) )) float float3;
 typedef __attribute__(( ext_vector_type(4) )) int int4;
Index: test/SemaOpenCL/bool-vectors.cl
===================================================================
--- /dev/null
+++ test/SemaOpenCL/bool-vectors.cl
@@ -0,0 +1,3 @@
+// RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only
+
+typedef __attribute__((ext_vector_type(16))) _Bool bool8; // expected-error{{invalid vector element type 'bool'}}