Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -613,6 +613,7 @@
 def err_opencl_half_load_store : Error<
   "%select{loading directly from|assigning directly to}0 pointer to type %1 is not allowed">;
 def err_opencl_cast_to_half : Error<"casting to type %0 is not allowed">;
+def err_opencl_cast_from_half : Error<"casting from type %0 is not allowed">;
 def err_opencl_half_declaration : Error<
   "declaring variable of type %0 is not allowed">;
 def err_opencl_half_param : Error<
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 +556,17 @@
   // we break out of the loop.
   for (; s != ThisTokEnd; ++s) {
     switch (*s) {
+    case 'h':      // FP Suffix for "half"
+    case 'H':
+      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 +578,7 @@
     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 +655,7 @@
       isUnsigned = false;
       isLongLong = false;
       isFloat = false;
+      isHalf = false;
       isImaginary = false;
       MicrosoftInteger = 0;
 
Index: lib/Sema/SemaCast.cpp
===================================================================
--- lib/Sema/SemaCast.cpp
+++ lib/Sema/SemaCast.cpp
@@ -2394,6 +2394,12 @@
       SrcExpr = ExprError();
       return;
     }
+    if (SrcType->isHalfType()) {
+      Self.Diag(SrcExpr.get()->getLocStart(), diag::err_opencl_cast_from_half)
+        << SrcType << SrcExpr.get()->getSourceRange();
+      SrcExpr = ExprError();
+      return;
+    }
   }
 
   // ARC imposes extra restrictions on casts.
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -3294,7 +3294,9 @@
 
   if (Literal.isFloatingLiteral()) {
     QualType Ty;
-    if (Literal.isFloat)
+    if (Literal.isHalf)
+      Ty = Context.HalfTy;
+    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
@@ -12,6 +12,7 @@
 
   float c = 1.0f;
   b = (half) c;  // expected-error{{casting to type 'half' is not allowed}}
+  c = (float) 1.0h;  // expected-error{{casting from type 'half' is not allowed}}
 
   half *allowed = &p[1];
   half *allowed2 = &*p;
@@ -31,6 +32,7 @@
 
   float c = 1.0f;
   b = (half) c;
+  b = 1.0h;
 
   half *allowed = &p[1];
   half *allowed2 = &*p;