Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -124,6 +124,8 @@
   InGroup<LiteralRange>;
 def warn_double_const_requires_fp64 : Warning<
   "double precision constant requires cl_khr_fp64, casting to single precision">;
+def err_half_const_requires_fp16 : Error<
+  "half precision constant requires cl_khr_fp16">;
 
 // C99 variable-length arrays
 def ext_vla : Extension<"variable length arrays are a C99 feature">,
Index: include/clang/Lex/LiteralSupport.h
===================================================================
--- include/clang/Lex/LiteralSupport.h
+++ include/clang/Lex/LiteralSupport.h
@@ -61,6 +61,7 @@
   bool isUnsigned : 1;
   bool isLong : 1;          // This is *not* set for long long.
   bool isLongLong : 1;
+  bool isHalf : 1;          // 1.0h
   bool isFloat : 1;         // 1.0f
   bool isImaginary : 1;     // 1.0i
   uint8_t MicrosoftInteger; // Microsoft suffix extension i8, i16, i32, or i64.
Index: lib/Lex/LiteralSupport.cpp
===================================================================
--- lib/Lex/LiteralSupport.cpp
+++ lib/Lex/LiteralSupport.cpp
@@ -522,6 +522,7 @@
   isLong = false;
   isUnsigned = false;
   isLongLong = false;
+  isHalf = false;
   isFloat = false;
   isImaginary = false;
   MicrosoftInteger = 0;
@@ -555,10 +556,18 @@
   // we break out of the loop.
   for (; s != ThisTokEnd; ++s) {
     switch (*s) {
+    case 'h':      // FP Suffix for "half"
+    case 'H':
+      // OpenCL Extension v1.2 s9.5 - h or H suffix for half type
+      if (!PP.getLangOpts().Half) break;
+      if (!isFPConstant) break;  // Error for integer constant.
+      if (isHalf || isFloat || isLong) break; // HH, FH, LH invalid.
+      isHalf = true;
+      continue;  // Success.
     case 'f':      // FP Suffix for "float"
     case 'F':
       if (!isFPConstant) break;  // Error for integer constant.
-      if (isFloat || isLong) break; // FF, LF invalid.
+      if (isHalf || isFloat || isLong) break; // HF, FF, LF invalid.
       isFloat = true;
       continue;  // Success.
     case 'u':
@@ -570,7 +579,7 @@
     case 'l':
     case 'L':
       if (isLong || isLongLong) break;  // Cannot be repeated.
-      if (isFloat) break;               // LF invalid.
+      if (isHalf || isFloat) break;     // LH, LF invalid.
 
       // Check for long long.  The L's need to be adjacent and the same case.
       if (s[1] == s[0]) {
@@ -647,6 +656,7 @@
       isUnsigned = false;
       isLongLong = false;
       isFloat = false;
+      isHalf = false;
       isImaginary = false;
       MicrosoftInteger = 0;
 
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -3294,7 +3294,14 @@
 
   if (Literal.isFloatingLiteral()) {
     QualType Ty;
-    if (Literal.isFloat)
+    if (Literal.isHalf){
+      if (getOpenCLOptions().cl_khr_fp16)
+        Ty = Context.HalfTy;
+      else {
+        Diag(Tok.getLocation(), diag::err_half_const_requires_fp16);
+        return ExprError();
+      }
+    } else if (Literal.isFloat)
       Ty = Context.FloatTy;
     else if (!Literal.isLong)
       Ty = Context.DoubleTy;
Index: test/Lexer/opencl-half-literal.cl
===================================================================
--- /dev/null
+++ test/Lexer/opencl-half-literal.cl
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 %s -fsyntax-only -verify
+
+#pragma OPENCL EXTENSION cl_khr_fp16 : enable
+
+constant half a = 1.0h; 
+constant half aa = 1.0H;
+constant half b = 1.0hh; // expected-error{{invalid suffix 'hh' on floating constant}}
+constant half c = 1.0fh; // expected-error{{invalid suffix 'fh' on floating constant}}
+constant half d = 1.0lh; // expected-error{{invalid suffix 'lh' on floating constant}}
+constant half e = 1.0hf; // expected-error{{invalid suffix 'hf' on floating constant}}
Index: test/SemaOpenCL/half.cl
===================================================================
--- test/SemaOpenCL/half.cl
+++ test/SemaOpenCL/half.cl
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only -Wno-unused-value
 
 #pragma OPENCL EXTENSION cl_khr_fp16 : disable
+constant float f = 1.0h; // expected-error{{half precision constant requires cl_khr_fp16}}
 
 half half_disabled(half *p, // expected-error{{declaring function return value of type 'half' is not allowed}}
                    half h)  // expected-error{{declaring function parameter of type 'half' is not allowed}}
@@ -12,6 +13,8 @@
 
   float c = 1.0f;
   b = (half) c;  // expected-error{{casting to type 'half' is not allowed}}
+  c = (float) 1.0h;  // expected-error{{half precision constant requires cl_khr_fp16}}
+  b = 1.0h; // expected-error{{half precision constant requires cl_khr_fp16}}
 
   half *allowed = &p[1];
   half *allowed2 = &*p;
@@ -22,6 +25,7 @@
 
 // Exactly the same as above but with the cl_khr_fp16 extension enabled.
 #pragma OPENCL EXTENSION cl_khr_fp16 : enable
+constant half a = 1.0h;
 half half_enabled(half *p, half h)
 {
   half a[2];
@@ -31,6 +35,8 @@
 
   float c = 1.0f;
   b = (half) c;
+  c = (float) 1.0h;
+  b = 1.0h;
 
   half *allowed = &p[1];
   half *allowed2 = &*p;
@@ -38,3 +44,7 @@
 
   return h;
 }
+
+#pragma OPENCL EXTENSION cl_khr_fp16 : disable
+constant float b = 1.0h; // expected-error{{half precision constant requires cl_khr_fp16}}
+