Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -1852,6 +1853,14 @@
   if (auto TagT = dyn_cast<TagType>(QT.getCanonicalType().getTypePtr()))
     Decl = TagT->getDecl();
   auto Loc = DS.getTypeSpecTypeLoc();
+
+  // Check extensions for vector types.
+  // e.g. double4 is not allowed when cl_khr_fp64 is absent.
+  if (QT->isExtVectorType()) {
+    auto TypePtr = QT->castAs<ExtVectorType>()->getElementType().getTypePtr();
+    return checkOpenCLDisabledTypeOrDecl(TypePtr, Loc, QT, OpenCLTypeExtMap);
+  }
+
   if (checkOpenCLDisabledTypeOrDecl(Decl, Loc, QT, OpenCLDeclExtMap))
     return true;
 
Index: test/SemaOpenCL/extensions.cl
===================================================================
--- test/SemaOpenCL/extensions.cl
+++ test/SemaOpenCL/extensions.cl
@@ -70,6 +70,13 @@
 // expected-error@-2{{use of type 'double' requires cl_khr_fp64 extension to be enabled}}
 #endif
 
+  typedef double double4 __attribute__((ext_vector_type(4)));
+  double4 d4 = {0.0f, 2.0f, 3.0f, 1.0f};
+#ifdef NOFP64
+// expected-error@-3 {{use of type 'double' requires cl_khr_fp64 extension to be enabled}}
+// expected-error@-3 {{use of type 'double4' (vector of 4 'double' values) requires cl_khr_fp64 extension to be enabled}}
+#endif
+
   (void) 1.0;
 
 #ifdef NOFP64