diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index d2add78cd8dc..8ed16ad59cd3 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -1694,6 +1694,9 @@ public:
   ///
   unsigned getNumArgs() const { return NumArgs; }
 
+  /// \brief Retrieve the call arguments.
+  Expr **getArgs() { return reinterpret_cast<Expr **>(SubExprs + ARGS_START); }
+  
   /// getArg - Return the specified argument.
   Expr *getArg(unsigned Arg) {
     assert(Arg < NumArgs && "Arg access out of range!");
@@ -2737,6 +2740,9 @@ public:
   /// pointers.
   unsigned getNumSubExprs() const { return NumExprs; }
 
+  /// \brief Retrieve the array of expressions.
+  Expr **getSubExprs() { return reinterpret_cast<Expr **>(SubExprs); }
+  
   /// getExpr - Return the Expr at the specified index.
   Expr *getExpr(unsigned Index) {
     assert((Index < NumExprs) && "Arg access out of range!");
@@ -2971,6 +2977,9 @@ public:
 
   unsigned getNumInits() const { return InitExprs.size(); }
 
+  /// \brief Retrieve the set of initializers.
+  Expr **getInits() { return reinterpret_cast<Expr **>(InitExprs.data()); }
+    
   const Expr *getInit(unsigned Init) const {
     assert(Init < getNumInits() && "Initializer access out of range!");
     return cast_or_null<Expr>(InitExprs[Init]);
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index bd7d3f09c386..5311d9c3a83e 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -21,11 +21,11 @@
 
 namespace clang {
 
-  class CXXConstructorDecl;
-  class CXXDestructorDecl;
-  class CXXMethodDecl;
-  class CXXTemporary;
-  class TemplateArgumentListInfo;
+class CXXConstructorDecl;
+class CXXDestructorDecl;
+class CXXMethodDecl;
+class CXXTemporary;
+class TemplateArgumentListInfo;
 
 //===--------------------------------------------------------------------===//
 // C++ Expressions.
@@ -1052,6 +1052,10 @@ public:
   }
 
   unsigned getNumPlacementArgs() const { return NumPlacementArgs; }
+  Expr **getPlacementArgs() { 
+    return reinterpret_cast<Expr **>(SubExprs + Array); 
+  }
+  
   Expr *getPlacementArg(unsigned i) {
     assert(i < NumPlacementArgs && "Index out of range");
     return cast<Expr>(SubExprs[Array + i]);
@@ -1070,6 +1074,11 @@ public:
   void setHasInitializer(bool V) { Initializer = V; }
 
   unsigned getNumConstructorArgs() const { return NumConstructorArgs; }
+  
+  Expr **getConstructorArgs() {
+    return reinterpret_cast<Expr **>(SubExprs + Array + NumPlacementArgs);
+  }
+  
   Expr *getConstructorArg(unsigned i) {
     assert(i < NumConstructorArgs && "Index out of range");
     return cast<Expr>(SubExprs[Array + NumPlacementArgs + i]);
diff --git a/clang/include/clang/AST/ExprObjC.h b/clang/include/clang/AST/ExprObjC.h
index 0eba6ba9f2e8..c89d4e34c118 100644
--- a/clang/include/clang/AST/ExprObjC.h
+++ b/clang/include/clang/AST/ExprObjC.h
@@ -746,11 +746,11 @@ public:
 
   /// \brief Retrieve the arguments to this message, not including the
   /// receiver.
-  Stmt **getArgs() {
-    return reinterpret_cast<Stmt **>(this + 1) + 1;
+  Expr **getArgs() {
+    return reinterpret_cast<Expr **>(this + 1) + 1;
   }
-  const Stmt * const *getArgs() const {
-    return reinterpret_cast<const Stmt * const *>(this + 1) + 1;
+  const Expr * const *getArgs() const {
+    return reinterpret_cast<const Expr * const *>(this + 1) + 1;
   }
 
   /// getArg - Return the specified argument.
@@ -792,10 +792,16 @@ public:
   typedef ExprIterator arg_iterator;
   typedef ConstExprIterator const_arg_iterator;
 
-  arg_iterator arg_begin() { return getArgs(); }
-  arg_iterator arg_end()   { return getArgs() + NumArgs; }
-  const_arg_iterator arg_begin() const { return getArgs(); }
-  const_arg_iterator arg_end() const { return getArgs() + NumArgs; }
+  arg_iterator arg_begin() { return reinterpret_cast<Stmt **>(getArgs()); }
+  arg_iterator arg_end()   { 
+    return reinterpret_cast<Stmt **>(getArgs() + NumArgs); 
+  }
+  const_arg_iterator arg_begin() const { 
+    return reinterpret_cast<Stmt const * const*>(getArgs()); 
+  }
+  const_arg_iterator arg_end() const { 
+    return reinterpret_cast<Stmt const * const*>(getArgs() + NumArgs); 
+  }
 
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index d8bb0af01838..3a71883419f3 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2300,7 +2300,7 @@ ObjCMessageExpr::ObjCMessageExpr(QualType T,
     SelectorLoc(SelLoc), LBracLoc(LBracLoc), RBracLoc(RBracLoc) 
 {
   setReceiverPointer(Receiver);
-  Stmt **MyArgs = getArgs();
+  Expr **MyArgs = getArgs();
   for (unsigned I = 0; I != NumArgs; ++I) {
     if (Args[I]->isTypeDependent())
       ExprBits.TypeDependent = true;
@@ -2331,7 +2331,7 @@ ObjCMessageExpr::ObjCMessageExpr(QualType T,
     SelectorLoc(SelLoc), LBracLoc(LBracLoc), RBracLoc(RBracLoc) 
 {
   setReceiverPointer(Receiver);
-  Stmt **MyArgs = getArgs();
+  Expr **MyArgs = getArgs();
   for (unsigned I = 0; I != NumArgs; ++I) {
     if (Args[I]->isTypeDependent())
       ExprBits.TypeDependent = true;
@@ -2928,10 +2928,10 @@ Stmt::child_iterator ObjCProtocolExpr::child_end() {
 Stmt::child_iterator ObjCMessageExpr::child_begin() {
   if (getReceiverKind() == Instance)
     return reinterpret_cast<Stmt **>(this + 1);
-  return getArgs();
+  return reinterpret_cast<Stmt **>(getArgs());
 }
 Stmt::child_iterator ObjCMessageExpr::child_end() {
-  return getArgs() + getNumArgs();
+  return reinterpret_cast<Stmt **>(getArgs() + getNumArgs());
 }
 
 // Blocks
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 992b84990468..03f5fc0c9a03 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -270,6 +270,33 @@ public:
   /// \returns the transformed expression.
   ExprResult TransformExpr(Expr *E);
 
+  /// \brief Transform the given list of expressions.
+  ///
+  /// This routine transforms a list of expressions by invoking 
+  /// \c TransformExpr() for each subexpression. However, it also provides 
+  /// support for variadic templates by expanding any pack expansions (if the
+  /// derived class permits such expansion) along the way. When pack expansions
+  /// are present, the number of outputs may not equal the number of inputs.
+  ///
+  /// \param Inputs The set of expressions to be transformed.
+  ///
+  /// \param NumInputs The number of expressions in \c Inputs.
+  ///
+  /// \param IsCall If \c true, then this transform is being performed on
+  /// function-call arguments, and any arguments that should be dropped, will 
+  /// be.
+  ///
+  /// \param Outputs The transformed input expressions will be added to this
+  /// vector.
+  ///
+  /// \param ArgChanged If non-NULL, will be set \c true if any argument changed
+  /// due to transformation.
+  ///
+  /// \returns true if an error occurred, false otherwise.
+  bool TransformExprs(Expr **Inputs, unsigned NumInputs, bool IsCall,
+                      llvm::SmallVectorImpl<Expr *> &Outputs,
+                      bool *ArgChanged = 0);
+  
   /// \brief Transform the given declaration, which is referenced from a type
   /// or expression.
   ///
@@ -2158,6 +2185,34 @@ ExprResult TreeTransform<Derived>::TransformExpr(Expr *E) {
   return SemaRef.Owned(E);
 }
 
+template<typename Derived>
+bool TreeTransform<Derived>::TransformExprs(Expr **Inputs, 
+                                            unsigned NumInputs, 
+                                            bool IsCall,
+                                      llvm::SmallVectorImpl<Expr *> &Outputs,
+                                            bool *ArgChanged) {
+  for (unsigned I = 0; I != NumInputs; ++I) {
+    // If requested, drop call arguments that need to be dropped.
+    if (IsCall && getDerived().DropCallArgument(Inputs[I])) {
+      if (ArgChanged)
+        *ArgChanged = true;
+      
+      break;
+    }
+    
+    ExprResult Result = getDerived().TransformExpr(Inputs[I]);
+    if (Result.isInvalid())
+      return true;
+    
+    if (Result.get() != Inputs[I] && ArgChanged)
+      *ArgChanged = true;
+    
+    Outputs.push_back(Result.get());    
+  }
+  
+  return false;
+}
+
 template<typename Derived>
 NestedNameSpecifier *
 TreeTransform<Derived>::TransformNestedNameSpecifier(NestedNameSpecifier *NNS,
@@ -4878,15 +4933,10 @@ TreeTransform<Derived>::TransformCallExpr(CallExpr *E) {
   // Transform arguments.
   bool ArgChanged = false;
   ASTOwningVector<Expr*> Args(SemaRef);
-  for (unsigned I = 0, N = E->getNumArgs(); I != N; ++I) {
-    ExprResult Arg = getDerived().TransformExpr(E->getArg(I));
-    if (Arg.isInvalid())
-      return ExprError();
-
-    ArgChanged = ArgChanged || Arg.get() != E->getArg(I);
-    Args.push_back(Arg.get());
-  }
-
+  if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args, 
+                                  &ArgChanged))
+    return ExprError();
+  
   if (!getDerived().AlwaysRebuild() &&
       Callee.get() == E->getCallee() &&
       !ArgChanged)
@@ -5114,15 +5164,10 @@ TreeTransform<Derived>::TransformInitListExpr(InitListExpr *E) {
   bool InitChanged = false;
 
   ASTOwningVector<Expr*, 4> Inits(SemaRef);
-  for (unsigned I = 0, N = E->getNumInits(); I != N; ++I) {
-    ExprResult Init = getDerived().TransformExpr(E->getInit(I));
-    if (Init.isInvalid())
-      return ExprError();
-
-    InitChanged = InitChanged || Init.get() != E->getInit(I);
-    Inits.push_back(Init.get());
-  }
-
+  if (getDerived().TransformExprs(E->getInits(), E->getNumInits(), false, 
+                                  Inits, &InitChanged))
+    return ExprError();
+  
   if (!getDerived().AlwaysRebuild() && !InitChanged)
     return SemaRef.Owned(E);
 
@@ -5242,15 +5287,10 @@ ExprResult
 TreeTransform<Derived>::TransformParenListExpr(ParenListExpr *E) {
   bool ArgumentChanged = false;
   ASTOwningVector<Expr*, 4> Inits(SemaRef);
-  for (unsigned I = 0, N = E->getNumExprs(); I != N; ++I) {
-    ExprResult Init = getDerived().TransformExpr(E->getExpr(I));
-    if (Init.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || Init.get() != E->getExpr(I);
-    Inits.push_back(Init.get());
-  }
-
+  if (TransformExprs(E->getExprs(), E->getNumExprs(), true, Inits,
+                     &ArgumentChanged))
+    return ExprError();
+  
   return getDerived().RebuildParenListExpr(E->getLParenLoc(),
                                            move_arg(Inits),
                                            E->getRParenLoc());
@@ -5344,16 +5384,9 @@ TreeTransform<Derived>::TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
 
     // Transform the call arguments.
     ASTOwningVector<Expr*> Args(SemaRef);
-    for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
-      if (getDerived().DropCallArgument(E->getArg(I)))
-        break;
-      
-      ExprResult Arg = getDerived().TransformExpr(E->getArg(I));
-      if (Arg.isInvalid())
-        return ExprError();
-
-      Args.push_back(Arg.release());
-    }
+    if (getDerived().TransformExprs(E->getArgs() + 1, E->getNumArgs() - 1, true, 
+                                    Args))
+      return ExprError();
 
     return getDerived().RebuildCallExpr(Object.get(), FakeLParenLoc,
                                         move_arg(Args),
@@ -5662,35 +5695,16 @@ TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
   // Transform the placement arguments (if any).
   bool ArgumentChanged = false;
   ASTOwningVector<Expr*> PlacementArgs(SemaRef);
-  for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I) {
-    if (getDerived().DropCallArgument(E->getPlacementArg(I))) {
-      ArgumentChanged = true;
-      break;
-    }
-
-    ExprResult Arg = getDerived().TransformExpr(E->getPlacementArg(I));
-    if (Arg.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || Arg.get() != E->getPlacementArg(I);
-    PlacementArgs.push_back(Arg.take());
-  }
+  if (getDerived().TransformExprs(E->getPlacementArgs(), 
+                                  E->getNumPlacementArgs(), true,
+                                  PlacementArgs, &ArgumentChanged))
+    return ExprError();  
 
   // transform the constructor arguments (if any).
   ASTOwningVector<Expr*> ConstructorArgs(SemaRef);
-  for (unsigned I = 0, N = E->getNumConstructorArgs(); I != N; ++I) {
-    if (getDerived().DropCallArgument(E->getConstructorArg(I))) {
-      ArgumentChanged = true;
-      break;
-    }
-    
-    ExprResult Arg = getDerived().TransformExpr(E->getConstructorArg(I));
-    if (Arg.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || Arg.get() != E->getConstructorArg(I);
-    ConstructorArgs.push_back(Arg.take());
-  }
+  if (TransformExprs(E->getConstructorArgs(), E->getNumConstructorArgs(), true,
+                     ConstructorArgs, &ArgumentChanged))
+    return ExprError();  
 
   // Transform constructor, new operator, and delete operator.
   CXXConstructorDecl *Constructor = 0;
@@ -6092,22 +6106,10 @@ TreeTransform<Derived>::TransformCXXConstructExpr(CXXConstructExpr *E) {
 
   bool ArgumentChanged = false;
   ASTOwningVector<Expr*> Args(SemaRef);
-  for (CXXConstructExpr::arg_iterator Arg = E->arg_begin(),
-       ArgEnd = E->arg_end();
-       Arg != ArgEnd; ++Arg) {
-    if (getDerived().DropCallArgument(*Arg)) {
-      ArgumentChanged = true;
-      break;
-    }
-
-    ExprResult TransArg = getDerived().TransformExpr(*Arg);
-    if (TransArg.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || TransArg.get() != *Arg;
-    Args.push_back(TransArg.get());
-  }
-
+  if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args, 
+                                  &ArgumentChanged))
+    return ExprError();
+  
   if (!getDerived().AlwaysRebuild() &&
       T == E->getType() &&
       Constructor == E->getConstructor() &&
@@ -6165,21 +6167,9 @@ TreeTransform<Derived>::TransformCXXTemporaryObjectExpr(
   bool ArgumentChanged = false;
   ASTOwningVector<Expr*> Args(SemaRef);
   Args.reserve(E->getNumArgs());
-  for (CXXTemporaryObjectExpr::arg_iterator Arg = E->arg_begin(),
-                                         ArgEnd = E->arg_end();
-       Arg != ArgEnd; ++Arg) {
-    if (getDerived().DropCallArgument(*Arg)) {
-      ArgumentChanged = true;
-      break;
-    }
-
-    ExprResult TransArg = getDerived().TransformExpr(*Arg);
-    if (TransArg.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || TransArg.get() != *Arg;
-    Args.push_back((Expr *)TransArg.release());
-  }
+  if (TransformExprs(E->getArgs(), E->getNumArgs(), true, Args, 
+                     &ArgumentChanged))
+    return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo() &&
@@ -6206,17 +6196,11 @@ TreeTransform<Derived>::TransformCXXUnresolvedConstructExpr(
 
   bool ArgumentChanged = false;
   ASTOwningVector<Expr*> Args(SemaRef);
-  for (CXXUnresolvedConstructExpr::arg_iterator Arg = E->arg_begin(),
-                                             ArgEnd = E->arg_end();
-       Arg != ArgEnd; ++Arg) {
-    ExprResult TransArg = getDerived().TransformExpr(*Arg);
-    if (TransArg.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || TransArg.get() != *Arg;
-    Args.push_back(TransArg.get());
-  }
-
+  Args.reserve(E->arg_size());
+  if (getDerived().TransformExprs(E->arg_begin(), E->arg_size(), true, Args, 
+                                  &ArgumentChanged))
+    return ExprError();
+  
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo() &&
       !ArgumentChanged)
@@ -6473,15 +6457,11 @@ TreeTransform<Derived>::TransformObjCMessageExpr(ObjCMessageExpr *E) {
   // Transform arguments.
   bool ArgChanged = false;
   ASTOwningVector<Expr*> Args(SemaRef);
-  for (unsigned I = 0, N = E->getNumArgs(); I != N; ++I) {
-    ExprResult Arg = getDerived().TransformExpr(E->getArg(I));
-    if (Arg.isInvalid())
-      return ExprError();
-    
-    ArgChanged = ArgChanged || Arg.get() != E->getArg(I);
-    Args.push_back(Arg.get());
-  }
-
+  Args.reserve(E->getNumArgs());
+  if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), false, Args, 
+                                  &ArgChanged))
+    return ExprError();
+  
   if (E->getReceiverKind() == ObjCMessageExpr::Class) {
     // Class message: transform the receiver type.
     TypeSourceInfo *ReceiverTypeInfo
@@ -6613,14 +6593,10 @@ ExprResult
 TreeTransform<Derived>::TransformShuffleVectorExpr(ShuffleVectorExpr *E) {
   bool ArgumentChanged = false;
   ASTOwningVector<Expr*> SubExprs(SemaRef);
-  for (unsigned I = 0, N = E->getNumSubExprs(); I != N; ++I) {
-    ExprResult SubExpr = getDerived().TransformExpr(E->getExpr(I));
-    if (SubExpr.isInvalid())
-      return ExprError();
-
-    ArgumentChanged = ArgumentChanged || SubExpr.get() != E->getExpr(I);
-    SubExprs.push_back(SubExpr.get());
-  }
+  SubExprs.reserve(E->getNumSubExprs());
+  if (getDerived().TransformExprs(E->getSubExprs(), E->getNumSubExprs(), false, 
+                                  SubExprs, &ArgumentChanged))
+    return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       !ArgumentChanged)