Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -716,9 +716,13 @@
   if (getLangOpts().ObjCAutoRefCount &&
       E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
     Cleanup.setExprNeedsCleanups(true);
+  
+  ExprResult Res = E;
 
-  ExprResult Res = ImplicitCastExpr::Create(Context, T, CK_LValueToRValue, E,
-                                            nullptr, VK_RValue);
+  if ( T != E->getType()) {
+    Res = ImplicitCastExpr::Create(Context, T, CK_LValueToRValue, E,
+                                   nullptr, VK_RValue);
+  }
 
   // C11 6.3.2.1p2:
   //   ... if the lvalue has atomic type, the value has the non-atomic version 
@@ -828,8 +832,20 @@
   // double.
   const BuiltinType *BTy = Ty->getAs<BuiltinType>();
   if (BTy && (BTy->getKind() == BuiltinType::Half ||
-              BTy->getKind() == BuiltinType::Float))
-    E = ImpCastExprToType(E, Context.DoubleTy, CK_FloatingCast).get();
+              BTy->getKind() == BuiltinType::Float)) {
+    if (getLangOpts().OpenCL &&
+        !((getLangOpts().OpenCLVersion >= 120 &&
+           Context.getTargetInfo()
+               .getSupportedOpenCLOpts()
+               .cl_khr_fp64) ||
+          getOpenCLOptions().cl_khr_fp64)) {
+        if (BTy->getKind() == BuiltinType::Half) {
+            E = ImpCastExprToType(E, Context.FloatTy, CK_FloatingCast).get();
+        }
+    } else {
+      E = ImpCastExprToType(E, Context.DoubleTy, CK_FloatingCast).get();
+    }
+  }
 
   // C++ performs lvalue-to-rvalue conversion as a default argument
   // promotion, even on class types, but note:
@@ -3404,10 +3420,19 @@
 
     if (Ty == Context.DoubleTy) {
       if (getLangOpts().SinglePrecisionConstants) {
-        Res = ImpCastExprToType(Res, Context.FloatTy, CK_FloatingCast).get();
+        const BuiltinType *BTy = Ty->getAs<BuiltinType>();
+        if (BTy->getKind() != BuiltinType::Float) {
+          Res = ImpCastExprToType(Res, Context.FloatTy, CK_FloatingCast).get();
+        }
       } else if (getLangOpts().OpenCL &&
-                 !((getLangOpts().OpenCLVersion >= 120) ||
+                 !((getLangOpts().OpenCLVersion >= 120 &&
+                    Context.getTargetInfo()
+                        .getSupportedOpenCLOpts()
+                        .cl_khr_fp64) ||
                    getOpenCLOptions().cl_khr_fp64)) {
+        // Impose single-precision float type when:
+        //  - in CL 1.2 or above and cl_khr_fp64 is not supported, or
+        //  - in CL 1.1 or below and cl_khr_fp64 is not enabled.
         Diag(Tok.getLocation(), diag::warn_double_const_requires_fp64);
         Res = ImpCastExprToType(Res, Context.FloatTy, CK_FloatingCast).get();
       }
Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -1401,7 +1401,8 @@
       Result = Context.DoubleTy;
 
     if (S.getLangOpts().OpenCL &&
-        !((S.getLangOpts().OpenCLVersion >= 120) ||
+        !((S.getLangOpts().OpenCLVersion >= 120 
+           && S.Context.getTargetInfo().getSupportedOpenCLOpts().cl_khr_fp64) ||
           S.getOpenCLOptions().cl_khr_fp64)) {
       S.Diag(DS.getTypeSpecTypeLoc(), diag::err_type_requires_extension)
           << Result << "cl_khr_fp64";
Index: test/CodeGenOpenCL/fpmath.cl
===================================================================
--- test/CodeGenOpenCL/fpmath.cl
+++ test/CodeGenOpenCL/fpmath.cl
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple spir-unknown-unknown | FileCheck --check-prefix=CHECK --check-prefix=NODIVOPT %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple spir-unknown-unknown -cl-fp32-correctly-rounded-divide-sqrt | FileCheck --check-prefix=CHECK --check-prefix=DIVOPT %s
+// RUN: %clang_cc1 %s -emit-llvm -o - -DNOFP64 -cl-std=CL1.1 -triple r600-unknown-unknown -target-cpu r600 -pedantic | FileCheck --check-prefix=CHECK-DBL %s
 
 typedef __attribute__(( ext_vector_type(4) )) float float4;
 
@@ -21,14 +22,26 @@
   return a / b;
 }
 
+void printf(constant char* fmt, ...);
+
+#ifndef NOFP64
 #pragma OPENCL EXTENSION cl_khr_fp64 : enable
+#endif
+void testdbllit(long *val) {
+  // CHECK-DBL: float 2.000000e+01
+  // CHECK: double 2.000000e+01
+  printf("%f", 20.0);
+}
 
+#ifndef NOFP64
+#pragma OPENCL EXTENSION cl_khr_fp64 : enable
 double dpscalardiv(double a, double b) {
   // CHECK: @dpscalardiv
   // CHECK: #[[ATTR]]
   // CHECK-NOT: !fpmath
   return a / b;
 }
+#endif
 
 // CHECK: attributes #[[ATTR]] = {
 // NODIVOPT: "correctly-rounded-divide-sqrt-fp-math"="false"
Index: test/SemaOpenCL/extensions.cl
===================================================================
--- test/SemaOpenCL/extensions.cl
+++ test/SemaOpenCL/extensions.cl
@@ -1,13 +1,16 @@
 // RUN: %clang_cc1 %s -triple spir-unknown-unknown -verify -pedantic -fsyntax-only
 // RUN: %clang_cc1 %s -triple spir-unknown-unknown -verify -pedantic -fsyntax-only -cl-std=CL1.1
+// RUN: %clang_cc1 %s -triple spir-unknown-unknown -verify -pedantic -fsyntax-only -cl-std=CL1.2 -DFP64
 
 // Test with a target not supporting fp64.
 // RUN: %clang_cc1 %s -triple r600-unknown-unknown -target-cpu r600 -verify -pedantic -fsyntax-only -DNOFP64
 
+#if __OPENCL_C_VERSION__ < 120
 void f1(double da) { // expected-error {{type 'double' requires cl_khr_fp64 extension}}
   double d; // expected-error {{type 'double' requires cl_khr_fp64 extension}}
   (void) 1.0; // expected-warning {{double precision constant requires cl_khr_fp64}}
 }
+#endif
 
 #pragma OPENCL EXTENSION cl_khr_fp64 : enable
 #ifdef NOFP64
@@ -21,8 +24,12 @@
 #endif
 
   (void) 1.0;
+#ifdef FP64
+// expected-no-diagnostics
+#endif
+
 #ifdef NOFP64
-// expected-warning@-2{{double precision constant requires cl_khr_fp64, casting to single precision}}
+// expected-warning@-6{{double precision constant requires cl_khr_fp64, casting to single precision}}
 #endif
 }
 
@@ -31,6 +38,8 @@
 // expected-warning@-2{{unsupported OpenCL extension 'cl_khr_fp64' - ignoring}}
 #endif
 
+#if __OPENCL_C_VERSION__ < 120
 void f3(void) {
   double d; // expected-error {{type 'double' requires cl_khr_fp64 extension}}
 }
+#endif