Index: include/clang/AST/OperationKinds.def
===================================================================
--- include/clang/AST/OperationKinds.def
+++ include/clang/AST/OperationKinds.def
@@ -321,6 +321,9 @@
 // Convert a zero value for OpenCL event_t initialization.
 CAST_OPERATION(ZeroToOCLEvent)
 
+// Convert a zero value for OpenCL queue_t initialization.
+CAST_OPERATION(ZeroToOCLQueue)
+
 // Convert a pointer to a different address space.
 CAST_OPERATION(AddressSpaceConversion)
 
Index: include/clang/Sema/Initialization.h
===================================================================
--- include/clang/Sema/Initialization.h
+++ include/clang/Sema/Initialization.h
@@ -724,6 +724,8 @@
     SK_StdInitializerListConstructorCall,
     /// \brief Initialize an OpenCL sampler from an integer.
     SK_OCLSamplerInit,
+    /// \brief Initialize queue_t from 0.
+    SK_OCLZeroQueue,
     /// \brief Passing zero to a function where OpenCL event_t is expected.
     SK_OCLZeroEvent
   };
@@ -1110,6 +1112,9 @@
   /// constant.
   void AddOCLZeroEventStep(QualType T);
 
+  /// \brief Add a step to initialize an OpenCL queue_t from 0.
+  void AddOCLZeroQueueStep(QualType T);
+
   /// \brief Add steps to unwrap a initializer list for a reference around a
   /// single element and rewrap it at the end.
   void RewrapReferenceInitList(QualType T, InitListExpr *Syntactic);
Index: include/clang/Sema/Overload.h
===================================================================
--- include/clang/Sema/Overload.h
+++ include/clang/Sema/Overload.h
@@ -83,6 +83,7 @@
     ICK_TransparentUnionConversion, ///< Transparent Union Conversions
     ICK_Writeback_Conversion,  ///< Objective-C ARC writeback conversion
     ICK_Zero_Event_Conversion, ///< Zero constant to event (OpenCL1.2 6.12.10)
+    ICK_Zero_Queue_Conversion, ///< Zero constant to queue
     ICK_C_Only_Conversion,     ///< Conversions allowed in C, but not C++
     ICK_Incompatible_Pointer_Conversion, ///< C-only conversion between pointers
                                          ///  with incompatible types
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -8257,6 +8257,7 @@
   case CK_IntegralComplexToFloatingComplex:
   case CK_BuiltinFnToFnPtr:
   case CK_ZeroToOCLEvent:
+  case CK_ZeroToOCLQueue:
   case CK_NonAtomicToAtomic:
   case CK_AddressSpaceConversion:
   case CK_IntToOCLSampler:
@@ -8749,6 +8750,7 @@
   case CK_CopyAndAutoreleaseBlockObject:
   case CK_BuiltinFnToFnPtr:
   case CK_ZeroToOCLEvent:
+  case CK_ZeroToOCLQueue:
   case CK_NonAtomicToAtomic:
   case CK_AddressSpaceConversion:
   case CK_IntToOCLSampler:
Index: lib/CodeGen/CGExprAgg.cpp
===================================================================
--- lib/CodeGen/CGExprAgg.cpp
+++ lib/CodeGen/CGExprAgg.cpp
@@ -749,6 +749,7 @@
   case CK_CopyAndAutoreleaseBlockObject:
   case CK_BuiltinFnToFnPtr:
   case CK_ZeroToOCLEvent:
+  case CK_ZeroToOCLQueue:
   case CK_AddressSpaceConversion:
   case CK_IntToOCLSampler:
     llvm_unreachable("cast kind invalid for aggregate types");
Index: lib/CodeGen/CGExprComplex.cpp
===================================================================
--- lib/CodeGen/CGExprComplex.cpp
+++ lib/CodeGen/CGExprComplex.cpp
@@ -480,6 +480,7 @@
   case CK_CopyAndAutoreleaseBlockObject:
   case CK_BuiltinFnToFnPtr:
   case CK_ZeroToOCLEvent:
+  case CK_ZeroToOCLQueue:
   case CK_AddressSpaceConversion:
   case CK_IntToOCLSampler:
     llvm_unreachable("invalid cast kind for complex value");
Index: lib/CodeGen/CGExprScalar.cpp
===================================================================
--- lib/CodeGen/CGExprScalar.cpp
+++ lib/CodeGen/CGExprScalar.cpp
@@ -1574,6 +1574,11 @@
     return llvm::Constant::getNullValue(ConvertType(DestTy));
   }
 
+  case CK_ZeroToOCLQueue: {
+    assert(DestTy->isQueueT() && "CK_ZeroToOCLQueue cast on non queue_t type");
+    return llvm::Constant::getNullValue(ConvertType(DestTy));
+  }
+
   case CK_IntToOCLSampler:
     return CGF.CGM.createOpenCLIntToSamplerConversion(E, CGF);
 
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -9621,6 +9621,18 @@
     return ResultTy;
   }
 
+  if (getLangOpts().OpenCLVersion >= 200) {
+    if (LHSIsNull && RHSType->isQueueT()) {
+      LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
+      return ResultTy;
+    }
+
+    if (LHSType->isQueueT() && RHSIsNull) {
+      RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
+      return ResultTy;
+    }
+  }
+
   return InvalidOperands(Loc, LHS, RHS);
 }
 
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -3882,6 +3882,12 @@
                              From->getValueKind()).get();
     break;
 
+  case ICK_Zero_Queue_Conversion:
+    From = ImpCastExprToType(From, ToType,
+                             CK_ZeroToOCLQueue,
+                             From->getValueKind()).get();
+    break;
+
   case ICK_Lvalue_To_Rvalue:
   case ICK_Array_To_Pointer:
   case ICK_Function_To_Pointer:
Index: lib/Sema/SemaInit.cpp
===================================================================
--- lib/Sema/SemaInit.cpp
+++ lib/Sema/SemaInit.cpp
@@ -3073,6 +3073,7 @@
   case SK_StdInitializerListConstructorCall:
   case SK_OCLSamplerInit:
   case SK_OCLZeroEvent:
+  case SK_OCLZeroQueue:
     break;
 
   case SK_ConversionSequence:
@@ -3334,6 +3335,13 @@
   Steps.push_back(S);
 }
 
+void InitializationSequence::AddOCLZeroQueueStep(QualType T) {
+  Step S;
+  S.Kind = SK_OCLZeroQueue;
+  S.Type = T;
+  Steps.push_back(S);
+}
+
 void InitializationSequence::RewrapReferenceInitList(QualType T,
                                                      InitListExpr *Syntactic) {
   assert(Syntactic->getNumInits() == 1 &&
@@ -4981,6 +4989,20 @@
   return true;
 }
 
+static bool TryOCLZeroQueueInitialization(Sema &S,
+                                          InitializationSequence &Sequence,
+                                          QualType DestType,
+                                          Expr *Initializer) {
+  if (!S.getLangOpts().OpenCL || S.getLangOpts().OpenCLVersion < 200 ||
+      !DestType->isQueueT() ||
+      !Initializer->isIntegerConstantExpr(S.getASTContext()) ||
+      (Initializer->EvaluateKnownConstInt(S.getASTContext()) != 0))
+    return false;
+
+  Sequence.AddOCLZeroQueueStep(DestType);
+  return true;
+}
+
 InitializationSequence::InitializationSequence(Sema &S,
                                                const InitializedEntity &Entity,
                                                const InitializationKind &Kind,
@@ -5179,6 +5201,9 @@
     if (TryOCLZeroEventInitialization(S, *this, DestType, Initializer))
       return;
 
+    if (TryOCLZeroQueueInitialization(S, *this, DestType, Initializer))
+       return;
+
     // Handle initialization in C
     AddCAssignmentStep(DestType);
     MaybeProduceObjCObject(S, *this, Entity);
@@ -6414,7 +6439,8 @@
   case SK_ProduceObjCObject:
   case SK_StdInitializerList:
   case SK_OCLSamplerInit:
-  case SK_OCLZeroEvent: {
+  case SK_OCLZeroEvent:
+  case SK_OCLZeroQueue: {
     assert(Args.size() == 1);
     CurInit = Args[0];
     if (!CurInit.get()) return ExprError();
@@ -7088,6 +7114,15 @@
                                     CurInit.get()->getValueKind());
       break;
     }
+    case SK_OCLZeroQueue: {
+      assert(Step->Type->isQueueT() &&
+             "Event initialization on non queue type.");
+
+      CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
+                                    CK_ZeroToOCLQueue,
+                                    CurInit.get()->getValueKind());
+      break;
+    }
     }
   }
 
@@ -7873,6 +7908,10 @@
     case SK_OCLZeroEvent:
       OS << "OpenCL event_t from zero";
       break;
+
+    case SK_OCLZeroQueue:
+      OS << "OpenCL queue_t from zero";
+      break;
     }
 
     OS << " [" << S->Type.getAsString() << ']';
Index: lib/Sema/SemaOverload.cpp
===================================================================
--- lib/Sema/SemaOverload.cpp
+++ lib/Sema/SemaOverload.cpp
@@ -1781,6 +1781,11 @@
              From->EvaluateKnownConstInt(S.getASTContext()) == 0) {
     SCS.Second = ICK_Zero_Event_Conversion;
     FromType = ToType;
+  } else if (ToType->isQueueT() &&
+             From->isIntegerConstantExpr(S.getASTContext()) &&
+             (From->EvaluateKnownConstInt(S.getASTContext()) == 0)) {
+    SCS.Second = ICK_Zero_Queue_Conversion;
+    FromType = ToType;
   } else {
     // No second conversion required.
     SCS.Second = ICK_Identity;
@@ -5155,6 +5160,7 @@
   case ICK_Function_Conversion:
   case ICK_Integral_Promotion:
   case ICK_Integral_Conversion: // Narrowing conversions are checked elsewhere.
+  case ICK_Zero_Queue_Conversion:
     return true;
 
   case ICK_Boolean_Conversion:
Index: test/CodeGenOpenCL/null_queue.cl
===================================================================
--- /dev/null
+++ test/CodeGenOpenCL/null_queue.cl
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -O0 -cl-std=CL2.0  -emit-llvm %s -o - | FileCheck %s
+extern queue_t get_default_queue();
+
+bool compare() {
+  return 0 == get_default_queue() &&
+         get_default_queue() == 0;
+  // CHECK: icmp eq %opencl.queue_t* null, %{{.*}}
+  // CHECK: icmp eq %opencl.queue_t* %{{.*}}, null
+}
+
+void func(queue_t q);
+
+void init() {
+  queue_t q = 0;
+  func(0);
+  // CHECK: store %opencl.queue_t* null, %opencl.queue_t** %q
+  // CHECK: call void @func(%opencl.queue_t* null)
+}
Index: test/SemaOpenCL/null_queue.cl
===================================================================
--- /dev/null
+++ test/SemaOpenCL/null_queue.cl
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -pedantic -fsyntax-only
+extern queue_t get_default_queue();
+
+bool compare() {
+  return 1 == get_default_queue() && // expected-error{{invalid operands to binary expression ('int' and 'queue_t')}}
+         get_default_queue() == 1; // expected-error{{invalid operands to binary expression ('queue_t' and 'int')}}
+}
+
+void init() {
+  queue_t q1 = 1; // expected-error{{initializing 'queue_t' with an expression of incompatible type 'int'}}
+  queue_t q = 0;
+}
Index: test/SemaOpenCL/queue_t_overload.cl
===================================================================
--- /dev/null
+++ test/SemaOpenCL/queue_t_overload.cl
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -pedantic -fsyntax-only
+
+void __attribute__((overloadable)) foo(queue_t, __local char *); // expected-note {{candidate function}}
+void __attribute__((overloadable)) foo(queue_t, __local float *); // expected-note {{candidate function}}
+
+void kernel ker(__local char *src1, __local float *src2, __global int *src3) {
+  queue_t q;
+  foo(q, src1);
+  foo(0, src2);
+  foo(q, src3); // expected-error {{call to 'foo' is ambiguous}}
+}