diff --git a/clang/include/clang/AST/Attr.h b/clang/include/clang/AST/Attr.h
index 287d80f93f49..feed54b7ecd5 100644
--- a/clang/include/clang/AST/Attr.h
+++ b/clang/include/clang/AST/Attr.h
@@ -66,6 +66,7 @@ public:
     Pure,
     Regparm,
     Section,
+    Sentinel,
     StdCall,
     TransparentUnion,
     Unavailable,
@@ -359,6 +360,23 @@ public:
   static bool classof(const FormatAttr *A) { return true; }
 };
 
+class SentinelAttr : public Attr {
+  int sentinel, NullPos;
+public:
+  SentinelAttr(int sentinel_val, int nullPos) : Attr(Sentinel),
+               sentinel(sentinel_val), NullPos(nullPos) {}
+  int getSentinel() const { return sentinel; }
+  int getNullPos() const { return NullPos; }
+
+  virtual Attr *clone(ASTContext &C) const {
+    return ::new (C) SentinelAttr(sentinel, NullPos);
+  }
+
+  // Implement isa/cast/dyncast/etc.
+  static bool classof(const Attr *A) { return A->getKind() == Sentinel; }
+  static bool classof(const SentinelAttr *A) { return true; }
+};
+
 class VisibilityAttr : public Attr {
 public:
   /// @brief An enumeration for the kinds of visibility of symbols.
diff --git a/clang/lib/Frontend/PCHReaderDecl.cpp b/clang/lib/Frontend/PCHReaderDecl.cpp
index e623b6f1d7d6..3db00ec1b71f 100644
--- a/clang/lib/Frontend/PCHReaderDecl.cpp
+++ b/clang/lib/Frontend/PCHReaderDecl.cpp
@@ -452,6 +452,13 @@ Attr *PCHReader::ReadAttributes() {
       New = ::new (*Context) FormatAttr(Type, FormatIdx, FirstArg);
       break;
     }
+        
+    case Attr::Sentinel: {
+      int sentinel = Record[Idx++];
+      int nullPos = Record[Idx++];
+      New = ::new (*Context) SentinelAttr(sentinel, nullPos);
+      break;
+    }
 
     SIMPLE_ATTR(GNUInline);
     
diff --git a/clang/lib/Frontend/PCHWriter.cpp b/clang/lib/Frontend/PCHWriter.cpp
index dbe0e536e557..e05a73568f4e 100644
--- a/clang/lib/Frontend/PCHWriter.cpp
+++ b/clang/lib/Frontend/PCHWriter.cpp
@@ -1556,6 +1556,13 @@ void PCHWriter::WriteAttributeRecord(const Attr *Attr) {
       break;
     }
 
+    case Attr::Sentinel : {
+      const SentinelAttr *Sentinel = cast<SentinelAttr>(Attr);
+      Record.push_back(Sentinel->getSentinel());
+      Record.push_back(Sentinel->getNullPos());
+      break;
+    }
+        
     case Attr::GNUInline:
     case Attr::IBOutletKind:
     case Attr::NoReturn:
diff --git a/clang/lib/Sema/Sema.h b/clang/lib/Sema/Sema.h
index 2e617f573bec..8c38c2bfd2bb 100644
--- a/clang/lib/Sema/Sema.h
+++ b/clang/lib/Sema/Sema.h
@@ -1274,6 +1274,8 @@ public:
   bool DiagnosePropertyAccessorMismatch(ObjCPropertyDecl *PD, 
                                         ObjCMethodDecl *Getter,
                                         SourceLocation Loc);
+  void DiagnoseSentinelCalls(NamedDecl *D, SourceLocation Loc,
+                             Expr **Args, unsigned NumArgs);
 
   // Primary Expressions.
   virtual SourceRange getExprRange(ExprTy *E) const;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index d2e84c10e222..f1da408669ca 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -88,6 +88,15 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc) {
   return false;
 }
 
+/// DiagnoseSentinelCalls - This routine checks on method dispatch calls
+/// (and other functions in future), which have been declared with sentinel 
+/// attribute. It warns if call does not have the sentinel argument.
+///
+void Sema::DiagnoseSentinelCalls(NamedDecl *D, SourceLocation Loc,
+                                 Expr **Args, unsigned NumArgs)
+{
+}
+
 SourceRange Sema::getExprRange(ExprTy *E) const {
   Expr *Ex = (Expr *)E;
   return Ex? Ex->getSourceRange() : SourceRange();
diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index de6b69f90fbe..0073fd9f28f2 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -626,6 +626,8 @@ Sema::ExprResult Sema::ActOnInstanceMessage(ExprTy *receiver, Selector Sel,
     return true;
   }
   
+  if (Method)
+    DiagnoseSentinelCalls(Method, receiverLoc, ArgExprs, NumArgs);
   if (CheckMessageArgumentTypes(ArgExprs, NumArgs, Sel, Method, false,
                                 lbrac, rbrac, returnType))
     return true;