diff --git a/include/clang/AST/ExprCXX.h b/include/clang/AST/ExprCXX.h
index cdabc75..704a97c 100644
--- a/include/clang/AST/ExprCXX.h
+++ b/include/clang/AST/ExprCXX.h
@@ -396,6 +396,74 @@
   virtual child_iterator child_end();
 };
 
+/// CXXUuidofExpr - A microsoft C++ @c __uuidof expression, which gets
+/// the _GUID that corresponds to the supplied type or expression.
+///
+/// This represents code like @c __uuidof(COMTYPE) or @c __uuidof(*comPtr)
+class CXXUuidofExpr : public Expr {
+private:
+  llvm::PointerUnion<Stmt *, TypeSourceInfo *> Operand;
+  SourceRange Range;
+
+public:
+  CXXUuidofExpr(QualType Ty, TypeSourceInfo *Operand, SourceRange R)
+    : Expr(CXXUuidofExprClass, Ty, 
+        false, Operand->getType()->isDependentType()),
+      Operand(Operand), Range(R) { }
+  
+  CXXUuidofExpr(QualType Ty, Expr *Operand, SourceRange R)
+    : Expr(CXXUuidofExprClass, Ty,
+        false, Operand->isTypeDependent()),
+      Operand(Operand), Range(R) { }
+
+  CXXUuidofExpr(EmptyShell Empty, bool isExpr)
+    : Expr(CXXUuidofExprClass, Empty) {
+    if (isExpr)
+      Operand = (Expr*)0;
+    else
+      Operand = (TypeSourceInfo*)0;
+  }
+  
+  bool isTypeOperand() const { return Operand.is<TypeSourceInfo *>(); }
+  
+  /// \brief Retrieves the type operand of this __uuidof() expression after
+  /// various required adjustments (removing reference types, cv-qualifiers).
+  QualType getTypeOperand() const;
+
+  /// \brief Retrieve source information for the type operand.
+  TypeSourceInfo *getTypeOperandSourceInfo() const {
+    assert(isTypeOperand() && "Cannot call getTypeOperand for __uuidof(expr)");
+    return Operand.get<TypeSourceInfo *>();
+  }
+
+  void setTypeOperandSourceInfo(TypeSourceInfo *TSI) {
+    assert(isTypeOperand() && "Cannot call getTypeOperand for __uuidof(expr)");
+    Operand = TSI;
+  }
+  
+  Expr *getExprOperand() const {
+    assert(!isTypeOperand() && "Cannot call getExprOperand for __uuidof(type)");
+    return static_cast<Expr*>(Operand.get<Stmt *>());
+  }
+  
+  void setExprOperand(Expr *E) {
+    assert(!isTypeOperand() && "Cannot call getExprOperand for __uuidof(type)");
+    Operand = E;
+  }
+
+  virtual SourceRange getSourceRange() const { return Range; }
+  void setSourceRange(SourceRange R) { Range = R; }
+  
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == CXXUuidofExprClass;
+  }
+  static bool classof(const CXXUuidofExpr *) { return true; }
+
+  // Iterators
+  virtual child_iterator child_begin();
+  virtual child_iterator child_end();
+};
+
 /// CXXThisExpr - Represents the "this" expression in C++, which is a
 /// pointer to the object on which the current member function is
 /// executing (C++ [expr.prim]p3). Example:
diff --git a/include/clang/AST/RecursiveASTVisitor.h b/include/clang/AST/RecursiveASTVisitor.h
index 88ffd5e..a41960d 100644
--- a/include/clang/AST/RecursiveASTVisitor.h
+++ b/include/clang/AST/RecursiveASTVisitor.h
@@ -1769,6 +1769,13 @@
       TRY_TO(TraverseTypeLoc(S->getTypeOperandSourceInfo()->getTypeLoc()));
   })
 
+DEF_TRAVERSE_STMT(CXXUuidofExpr, {
+    // The child-iterator will pick up the arg if it's an expression,
+    // but not if it's a type.
+    if (S->isTypeOperand())
+      TRY_TO(TraverseTypeLoc(S->getTypeOperandSourceInfo()->getTypeLoc()));
+  })
+
 DEF_TRAVERSE_STMT(TypesCompatibleExpr, {
     TRY_TO(TraverseTypeLoc(S->getArgTInfo1()->getTypeLoc()));
     TRY_TO(TraverseTypeLoc(S->getArgTInfo2()->getTypeLoc()));
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 438d0fc..91b0b6a 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2392,6 +2392,8 @@
 // Other C++ expressions
 def err_need_header_before_typeid : Error<
   "you need to include <typeinfo> before using the 'typeid' operator">;
+def err_need_header_before_ms_uuidof : Error<
+  "you need to include <guiddef.h> before using the '__uuidof' operator">;
 def err_incomplete_typeid : Error<"'typeid' of incomplete type %0">;
 def err_static_illegal_in_new : Error<
   "the 'static' modifier for the array size is not legal in new expressions">;
diff --git a/include/clang/Basic/StmtNodes.td b/include/clang/Basic/StmtNodes.td
index 4aa055e..7778a6d 100644
--- a/include/clang/Basic/StmtNodes.td
+++ b/include/clang/Basic/StmtNodes.td
@@ -127,3 +127,7 @@
 def ShuffleVectorExpr : DStmt<Expr>;
 def BlockExpr : DStmt<Expr>;
 def BlockDeclRefExpr : DStmt<Expr>;
+
+// Microsoft Extensions.
+def CXXUuidofExpr : DStmt<Expr>; 
+
diff --git a/include/clang/Basic/TokenKinds.def b/include/clang/Basic/TokenKinds.def
index dc360ad..18f29c2 100644
--- a/include/clang/Basic/TokenKinds.def
+++ b/include/clang/Basic/TokenKinds.def
@@ -369,11 +369,13 @@
 // Microsoft extensions which should be disabled in strict conformance mode
 KEYWORD(__ptr64                   , KEYMS)
 KEYWORD(__w64                     , KEYMS)
+KEYWORD(__uuidof                  , KEYMS)
 ALIAS("_asm"         , asm        , KEYMS)
 ALIAS("_cdecl"       , __cdecl    , KEYMS)
 ALIAS("_fastcall"    , __fastcall , KEYMS)
 ALIAS("_stdcall"     , __stdcall  , KEYMS)
 ALIAS("_thiscall"    , __thiscall , KEYMS)
+ALIAS("_uuidof"      ,__uuidof    , KEYMS)
 
 // Borland Extensions which should be disabled in strict conformance mode.
 ALIAS("_pascal"      , __pascal   , KEYBORLAND)
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index 9c1630e..a7dab1e 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -1029,6 +1029,10 @@
   ExprResult ParseCXXTypeid();
 
   //===--------------------------------------------------------------------===//
+  //  C++ : Microsoft __uuidof Expression
+  ExprResult ParseCXXUuidof();
+
+  //===--------------------------------------------------------------------===//
   // C++ 5.2.4: C++ Pseudo-Destructor Expressions
   ExprResult ParseCXXPseudoDestructor(ExprArg Base, SourceLocation OpLoc,
                                             tok::TokenKind OpKind,
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 0911986..845f4a5 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -365,6 +365,9 @@
   /// standard library.
   LazyDeclPtr StdBadAlloc;
 
+  /// \brief The MSVC "_GUID" struct, which is defined in MSVC header files.
+  RecordDecl *MSVCGuidDecl;
+
   /// A flag to remember whether the implicit forms of operator new and delete
   /// have been declared.
   bool GlobalNewDeleteDeclared;
@@ -2156,6 +2159,22 @@
                             void *TyOrExpr,
                             SourceLocation RParenLoc);
 
+  ExprResult BuildCXXUuidof(QualType TypeInfoType,
+                            SourceLocation TypeidLoc,
+                            TypeSourceInfo *Operand,
+                            SourceLocation RParenLoc);
+  ExprResult BuildCXXUuidof(QualType TypeInfoType,
+                            SourceLocation TypeidLoc,
+                            Expr *Operand,
+                            SourceLocation RParenLoc);
+
+  /// ActOnCXXUuidof - Parse __uuidof( something ).
+  virtual ExprResult ActOnCXXUuidof(SourceLocation OpLoc,
+                                    SourceLocation LParenLoc, bool isType,
+                                    void *TyOrExpr,
+                                    SourceLocation RParenLoc);
+
+
   //// ActOnCXXThis -  Parse 'this' pointer.
   ExprResult ActOnCXXThis(SourceLocation ThisLoc);
 
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 0fa446d..f50b228 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -875,6 +875,8 @@
       EXPR_CXX_NULL_PTR_LITERAL,  // CXXNullPtrLiteralExpr
       EXPR_CXX_TYPEID_EXPR,       // CXXTypeidExpr (of expr).
       EXPR_CXX_TYPEID_TYPE,       // CXXTypeidExpr (of type).
+      EXPR_CXX_UUIDOF_EXPR,       // CXXUuidofExpr (of expr).
+      EXPR_CXX_UUIDOF_TYPE,       // CXXUuidofExpr (of type).
       EXPR_CXX_THIS,              // CXXThisExpr
       EXPR_CXX_THROW,             // CXXThrowExpr
       EXPR_CXX_DEFAULT_ARG,       // CXXDefaultArgExpr
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index 8caf70b..f72ab98 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -39,6 +39,22 @@
                          : reinterpret_cast<Stmt **>(&Operand) + 1;
 }
 
+QualType CXXUuidofExpr::getTypeOperand() const {
+  assert(isTypeOperand() && "Cannot call getTypeOperand for __uuidof(expr)");
+  return Operand.get<TypeSourceInfo *>()->getType().getNonReferenceType()
+                                                        .getUnqualifiedType();
+}
+
+// CXXUuidofExpr - has child iterators if the operand is an expression
+Stmt::child_iterator CXXUuidofExpr::child_begin() {
+  return isTypeOperand() ? child_iterator() 
+                         : reinterpret_cast<Stmt **>(&Operand);
+}
+Stmt::child_iterator CXXUuidofExpr::child_end() {
+  return isTypeOperand() ? child_iterator() 
+                         : reinterpret_cast<Stmt **>(&Operand) + 1;
+}
+
 // CXXBoolLiteralExpr
 Stmt::child_iterator CXXBoolLiteralExpr::child_begin() {
   return child_iterator();
diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index 1778ce8..88e047d 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -1002,6 +1002,16 @@
   OS << ")";
 }
 
+void StmtPrinter::VisitCXXUuidofExpr(CXXUuidofExpr *Node) {
+  OS << "__uuidof(";
+  if (Node->isTypeOperand()) {
+    OS << Node->getTypeOperand().getAsString(Policy);
+  } else {
+    PrintExpr(Node->getExprOperand());
+  }
+  OS << ")";
+}
+
 void StmtPrinter::VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *Node) {
   OS << (Node->getValue() ? "true" : "false");
 }
diff --git a/lib/AST/StmtProfile.cpp b/lib/AST/StmtProfile.cpp
index 78a336d..843248c 100644
--- a/lib/AST/StmtProfile.cpp
+++ b/lib/AST/StmtProfile.cpp
@@ -687,6 +687,12 @@
     VisitType(S->getTypeOperand());
 }
 
+void StmtProfiler::VisitCXXUuidofExpr(CXXUuidofExpr *S) {
+  VisitExpr(S);
+  if (S->isTypeOperand())
+    VisitType(S->getTypeOperand());
+}
+
 void StmtProfiler::VisitCXXThisExpr(CXXThisExpr *S) {
   VisitExpr(S);
 }
diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index c4beab1..6a7c723 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -768,6 +768,9 @@
   case tok::kw_typeid:
     Res = ParseCXXTypeid();
     break;
+  case tok::kw___uuidof:
+    Res = ParseCXXUuidof();
+    break;
   case tok::kw_this:
     Res = ParseCXXThis();
     break;
diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index c48ae7c..18259ce 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -534,6 +534,54 @@
   return move(Result);
 }
 
+/// ParseCXXUuidof - This handles the Microsoft C++ __uuidof expression.
+///
+///         '__uuidof' '(' expression ')'
+///         '__uuidof' '(' type-id ')'
+///
+ExprResult Parser::ParseCXXUuidof() {
+  assert(Tok.is(tok::kw___uuidof) && "Not '__uuidof'!");
+
+  SourceLocation OpLoc = ConsumeToken();
+  SourceLocation LParenLoc = Tok.getLocation();
+  SourceLocation RParenLoc;
+
+  // __uuidof expressions are always parenthesized.
+  if (ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after,
+      "__uuidof"))
+    return ExprError();
+
+  ExprResult Result;
+
+  if (isTypeIdInParens()) {
+    TypeResult Ty = ParseTypeName();
+
+    // Match the ')'.
+    RParenLoc = MatchRHSPunctuation(tok::r_paren, LParenLoc);
+
+    if (Ty.isInvalid())
+      return ExprError();
+
+    Result = Actions.ActOnCXXUuidof(OpLoc, LParenLoc, /*isType=*/true,
+                                    Ty.get().getAsOpaquePtr(), RParenLoc);
+  } else {
+    EnterExpressionEvaluationContext Unevaluated(Actions, Sema::Unevaluated);
+    Result = ParseExpression();
+
+    // Match the ')'.
+    if (Result.isInvalid())
+      SkipUntil(tok::r_paren);
+    else {
+      RParenLoc = MatchRHSPunctuation(tok::r_paren, LParenLoc);
+
+      Result = Actions.ActOnCXXUuidof(OpLoc, LParenLoc, /*isType=*/false,
+                                      Result.release(), RParenLoc);
+    }
+  }
+
+  return move(Result);
+}
+
 /// \brief Parse a C++ pseudo-destructor expression after the base,
 /// . or -> operator, and nested-name-specifier have already been
 /// parsed.
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index 17817d4..60e8c14 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -138,7 +138,7 @@
     CompleteTranslationUnit(CompleteTranslationUnit),
     NumSFINAEErrors(0), SuppressAccessChecking(false),
     NonInstantiationEntries(0), CurrentInstantiationScope(0), TyposCorrected(0),
-    AnalysisWarnings(*this)
+    AnalysisWarnings(*this), MSVCGuidDecl(0)
 {
   TUScope = 0;
   if (getLangOptions().CPlusPlus)
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 7857ea9..c3e2c50 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -370,6 +370,62 @@
   return BuildCXXTypeId(TypeInfoType, OpLoc, (Expr*)TyOrExpr, RParenLoc);
 }
 
+/// \brief Build a Microsoft __uuidof expression with a type operand.
+ExprResult Sema::BuildCXXUuidof(QualType TypeInfoType,
+                                SourceLocation TypeidLoc,
+                                TypeSourceInfo *Operand,
+                                SourceLocation RParenLoc) {
+  // FIXME: add __uuidof semantic analysis for type operand.
+  return Owned(new (Context) CXXUuidofExpr(TypeInfoType.withConst(),
+                                           Operand,
+                                           SourceRange(TypeidLoc, RParenLoc)));
+}
+
+/// \brief Build a Microsoft __uuidof expression with an expression operand.
+ExprResult Sema::BuildCXXUuidof(QualType TypeInfoType,
+                                SourceLocation TypeidLoc,
+                                Expr *E,
+                                SourceLocation RParenLoc) {
+  // FIXME: add __uuidof semantic analysis for expr operand.
+  return Owned(new (Context) CXXUuidofExpr(TypeInfoType.withConst(),
+                                           E,
+                                           SourceRange(TypeidLoc, RParenLoc)));  
+}
+
+/// ActOnCXXUuidof - Parse __uuidof( type-id ) or __uuidof (expression);
+ExprResult
+Sema::ActOnCXXUuidof(SourceLocation OpLoc, SourceLocation LParenLoc,
+                     bool isType, void *TyOrExpr, SourceLocation RParenLoc) {
+  // If MSVCGuidDecl has not been cached, do the lookup. 
+  if (!MSVCGuidDecl) {
+    IdentifierInfo *GuidII = &PP.getIdentifierTable().get("_GUID");
+    LookupResult R(*this, GuidII, SourceLocation(), LookupTagName);
+    LookupQualifiedName(R, Context.getTranslationUnitDecl());
+    MSVCGuidDecl = R.getAsSingle<RecordDecl>();
+    if (!MSVCGuidDecl)
+      return ExprError(Diag(OpLoc, diag::err_need_header_before_ms_uuidof));
+  }  
+  
+  QualType GuidType = Context.getTypeDeclType(MSVCGuidDecl);
+  
+  if (isType) {
+    // The operand is a type; handle it as such.
+    TypeSourceInfo *TInfo = 0;
+    QualType T = GetTypeFromParser(ParsedType::getFromOpaquePtr(TyOrExpr),
+                                   &TInfo);
+    if (T.isNull())
+      return ExprError();
+    
+    if (!TInfo)
+      TInfo = Context.getTrivialTypeSourceInfo(T, OpLoc);
+
+    return BuildCXXUuidof(GuidType, OpLoc, TInfo, RParenLoc);
+  }
+
+  // The operand is an expression.  
+  return BuildCXXUuidof(GuidType, OpLoc, (Expr*)TyOrExpr, RParenLoc);
+}
+
 /// ActOnCXXBoolLiteral - Parse {true,false} literals.
 ExprResult
 Sema::ActOnCXXBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind) {
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 16114f2..746d6ca 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -1513,6 +1513,7 @@
                                     RParenLoc);
   }
 
+
   /// \brief Build a new C++ typeid(expr) expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
@@ -1525,6 +1526,30 @@
                                     RParenLoc);
   }
 
+  /// \brief Build a new C++ __uuidof(type) expression.
+  ///
+  /// By default, performs semantic analysis to build the new expression.
+  /// Subclasses may override this routine to provide different behavior.
+  ExprResult RebuildCXXUuidofExpr(QualType TypeInfoType,
+                                        SourceLocation TypeidLoc,
+                                        TypeSourceInfo *Operand,
+                                        SourceLocation RParenLoc) {
+    return getSema().BuildCXXUuidof(TypeInfoType, TypeidLoc, Operand, 
+                                    RParenLoc);
+  }
+
+  /// \brief Build a new C++ __uuidof(expr) expression.
+  ///
+  /// By default, performs semantic analysis to build the new expression.
+  /// Subclasses may override this routine to provide different behavior.
+  ExprResult RebuildCXXUuidofExpr(QualType TypeInfoType,
+                                        SourceLocation TypeidLoc,
+                                        Expr *Operand,
+                                        SourceLocation RParenLoc) {
+    return getSema().BuildCXXUuidof(TypeInfoType, TypeidLoc, Operand,
+                                    RParenLoc);
+  }
+
   /// \brief Build a new C++ "this" expression.
   ///
   /// By default, builds a new "this" expression without performing any
@@ -5145,6 +5170,44 @@
 
 template<typename Derived>
 ExprResult
+TreeTransform<Derived>::TransformCXXUuidofExpr(CXXUuidofExpr *E) {
+  if (E->isTypeOperand()) {
+    TypeSourceInfo *TInfo
+      = getDerived().TransformType(E->getTypeOperandSourceInfo());
+    if (!TInfo)
+      return ExprError();
+
+    if (!getDerived().AlwaysRebuild() &&
+        TInfo == E->getTypeOperandSourceInfo())
+      return SemaRef.Owned(E->Retain());
+
+    return getDerived().RebuildCXXTypeidExpr(E->getType(),
+                                             E->getLocStart(),
+                                             TInfo,
+                                             E->getLocEnd());
+  }
+
+  // We don't know whether the expression is potentially evaluated until
+  // after we perform semantic analysis, so the expression is potentially
+  // potentially evaluated.
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
+
+  ExprResult SubExpr = getDerived().TransformExpr(E->getExprOperand());
+  if (SubExpr.isInvalid())
+    return ExprError();
+
+  if (!getDerived().AlwaysRebuild() &&
+      SubExpr.get() == E->getExprOperand())
+    return SemaRef.Owned(E->Retain());
+
+  return getDerived().RebuildCXXUuidofExpr(E->getType(),
+                                           E->getLocStart(),
+                                           SubExpr.get(),
+                                           E->getLocEnd());
+}
+
+template<typename Derived>
+ExprResult
 TreeTransform<Derived>::TransformCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) {
   return SemaRef.Owned(E->Retain());
 }
diff --git a/lib/Serialization/ASTReaderStmt.cpp b/lib/Serialization/ASTReaderStmt.cpp
index 8bfca94..9366445 100644
--- a/lib/Serialization/ASTReaderStmt.cpp
+++ b/lib/Serialization/ASTReaderStmt.cpp
@@ -134,6 +134,7 @@
     void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E);
     void VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E);
     void VisitCXXTypeidExpr(CXXTypeidExpr *E);
+    void VisitCXXUuidofExpr(CXXUuidofExpr *E);
     void VisitCXXThisExpr(CXXThisExpr *E);
     void VisitCXXThrowExpr(CXXThrowExpr *E);
     void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E);
@@ -1028,6 +1029,18 @@
   // typeid(42+2)
   E->setExprOperand(Reader.ReadSubExpr());
 }
+void ASTStmtReader::VisitCXXUuidofExpr(CXXUuidofExpr *E) {
+  VisitExpr(E);
+  E->setSourceRange(Reader.ReadSourceRange(Record, Idx));
+  if (E->isTypeOperand()) { // __uuidof(ComType)
+    E->setTypeOperandSourceInfo(
+        Reader.GetTypeSourceInfo(DeclsCursor, Record, Idx));
+    return;
+  }
+  
+  // __uuidof(expr)
+  E->setExprOperand(Reader.ReadSubExpr());
+}
 
 void ASTStmtReader::VisitCXXThisExpr(CXXThisExpr *E) {
   VisitExpr(E);
@@ -1678,6 +1691,12 @@
     case EXPR_CXX_TYPEID_TYPE:
       S = new (Context) CXXTypeidExpr(Empty, false);
       break;
+    case EXPR_CXX_UUIDOF_EXPR:
+      S = new (Context) CXXUuidofExpr(Empty, true);
+      break;
+    case EXPR_CXX_UUIDOF_TYPE:
+      S = new (Context) CXXUuidofExpr(Empty, false);
+      break;
     case EXPR_CXX_THIS:
       S = new (Context) CXXThisExpr(Empty);
       break;
diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index cda42e1..403311b 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -131,6 +131,7 @@
     void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E);
     void VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E);
     void VisitCXXTypeidExpr(CXXTypeidExpr *E);
+    void VisitCXXUuidofExpr(CXXUuidofExpr *E);
     void VisitCXXThisExpr(CXXThisExpr *E);
     void VisitCXXThrowExpr(CXXThrowExpr *E);
     void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E);
@@ -1039,6 +1040,18 @@
   }
 }
 
+void ASTStmtWriter::VisitCXXUuidofExpr(CXXUuidofExpr *E) {
+  VisitExpr(E);
+  Writer.AddSourceRange(E->getSourceRange(), Record);
+  if (E->isTypeOperand()) {
+    Writer.AddTypeSourceInfo(E->getTypeOperandSourceInfo(), Record);
+    Code = serialization::EXPR_CXX_UUIDOF_TYPE;
+  } else {
+    Writer.AddStmt(E->getExprOperand());
+    Code = serialization::EXPR_CXX_UUIDOF_EXPR;
+  }
+}
+
 void ASTStmtWriter::VisitCXXThisExpr(CXXThisExpr *E) {
   VisitExpr(E);
   Writer.AddSourceLocation(E->getLocation(), Record);
diff --git a/test/Parser/MicrosoftExtensions.c b/test/Parser/MicrosoftExtensions.c
index ec272cd..105bb7f 100644
--- a/test/Parser/MicrosoftExtensions.c
+++ b/test/Parser/MicrosoftExtensions.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple i386-mingw32 -fsyntax-only -verify -fms-extensions -Wno-missing-declarations -x objective-c++ %s
+// RUN: %clang_cc1 -triple i386-mingw32 -fsyntax-only -verify -fms-extensions -Wno-unused-value -Wno-missing-declarations -x objective-c++ %s
 __stdcall int func0();
 int __stdcall func();
 typedef int (__cdecl *tptr)();
@@ -36,3 +36,40 @@
 char x = FOO(a);
 
 typedef enum E { e1 };
+
+
+void uuidof_test1()
+{  
+  __uuidof(0);  // expected-error {{you need to include <guiddef.h> before using the '__uuidof' operator}}
+}
+
+typedef struct _GUID
+{
+    unsigned long  Data1;
+    unsigned short Data2;
+    unsigned short Data3;
+    unsigned char  Data4[8];
+} GUID;
+struct __declspec(uuid("00000000-0000-0000-3231-000000000046")) A { };
+struct __declspec(uuid("00000000-0000-0000-1234-000000000047")) B { };
+class C {};
+
+void uuidof_test2()
+{
+  A* a = new A;
+  B b;
+  __uuidof(A);
+  __uuidof(*a);
+  __uuidof(B);
+  __uuidof(&b);
+  _uuidof(0);
+
+   // FIXME, this must not compile
+  _uuidof(1);
+   // FIXME, this must not compile
+  _uuidof(C);
+
+   C c;
+   // FIXME, this must not compile
+  _uuidof(c);
+}