diff --git a/Sema/Sema.h b/Sema/Sema.h
index 2c753f3..465e3fb 100644
--- a/Sema/Sema.h
+++ b/Sema/Sema.h
@@ -47,6 +47,7 @@
   class OCUVectorType;
   class TypedefDecl;
   class ObjcInterfaceDecl;
+  class ObjcProtocolDecl;
 
 /// Sema - This implements semantic analysis and AST building for C.
 class Sema : public Action {
@@ -185,6 +186,8 @@
                                SourceLocation IdLoc, Scope *S);  
   ObjcInterfaceDecl *getObjCInterfaceDecl(Scope *S, 
 		       IdentifierInfo *Id, SourceLocation IdLoc);
+  ObjcProtocolDecl *getObjCProtocolDecl(Scope *S, 
+		       IdentifierInfo *Id, SourceLocation IdLoc);
   ScopedDecl *LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID, Scope *S);
   ScopedDecl *ImplicitlyDefineFunction(SourceLocation Loc, IdentifierInfo &II,
                                  Scope *S);
diff --git a/Sema/SemaDecl.cpp b/Sema/SemaDecl.cpp
index 2b0e145..5e66684 100644
--- a/Sema/SemaDecl.cpp
+++ b/Sema/SemaDecl.cpp
@@ -78,7 +78,7 @@
   }
 }
 
-/// ObjcInterfaceDecl - Look up a for a class declaration in the scope.
+/// getObjcInterfaceDecl - Look up a for a class declaration in the scope.
 /// return 0 if one not found.
 ObjcInterfaceDecl *Sema::getObjCInterfaceDecl(Scope *S,
                        			      IdentifierInfo *Id, 
@@ -90,6 +90,19 @@
   return cast_or_null<ObjcInterfaceDecl>(static_cast<Decl*>(IdDecl));
 }
 
+/// getObjcProtocolDecl - Look up a for a protocol declaration in the scope.
+/// return 0 if one not found.
+ObjcProtocolDecl *Sema::getObjCProtocolDecl(Scope *S,
+                       			    IdentifierInfo *Id, 
+				            SourceLocation IdLoc) {
+  // Note that Protocols have their own namespace.
+  ScopedDecl *PrDecl = LookupScopedDecl(Id, Decl::IDNS_Protocol, 
+				        IdLoc, S);
+  if (PrDecl && !isa<ObjcProtocolDecl>(PrDecl))
+    PrDecl = 0;
+  return cast_or_null<ObjcProtocolDecl>(static_cast<Decl*>(PrDecl));
+}
+
 /// LookupScopedDecl - Look up the inner-most declaration in the specified
 /// namespace.
 ScopedDecl *Sema::LookupScopedDecl(IdentifierInfo *II, unsigned NSI,
@@ -935,7 +948,8 @@
   
   /// Check then save referenced protocols
   for (unsigned int i = 0; i != NumProtocols; i++) {
-    ObjcProtocolDecl* RefPDecl = Context.getObjCProtocolDecl(ProtocolNames[i]);
+    ObjcProtocolDecl* RefPDecl = getObjCProtocolDecl(S, ProtocolNames[i], 
+						     ClassLoc);
     if (!RefPDecl || RefPDecl->getIsForwardProtoDecl())
       Diag(ClassLoc, diag::err_undef_protocolref,
            ProtocolNames[i]->getName(),
@@ -951,7 +965,7 @@
                 IdentifierInfo *ProtocolName, SourceLocation ProtocolLoc,
                 IdentifierInfo **ProtoRefNames, unsigned NumProtoRefs) {
   assert(ProtocolName && "Missing protocol identifier");
-  ObjcProtocolDecl *PDecl = Context.getObjCProtocolDecl(ProtocolName);
+  ObjcProtocolDecl *PDecl = getObjCProtocolDecl(S, ProtocolName, ProtocolLoc);
   if (PDecl) {
     // Protocol already seen. Better be a forward protocol declaration
     if (!PDecl->getIsForwardProtoDecl())
@@ -969,12 +983,12 @@
     // Chain & install the protocol decl into the identifier.
     PDecl->setNext(ProtocolName->getFETokenInfo<ScopedDecl>());
     ProtocolName->setFETokenInfo(PDecl);
-    Context.setObjCProtocolDecl(ProtocolName, PDecl);
   }    
   
   /// Check then save referenced protocols
   for (unsigned int i = 0; i != NumProtoRefs; i++) {
-    ObjcProtocolDecl* RefPDecl = Context.getObjCProtocolDecl(ProtoRefNames[i]);
+    ObjcProtocolDecl* RefPDecl = getObjCProtocolDecl(S, ProtoRefNames[i], 
+						     ProtocolLoc);
     if (!RefPDecl || RefPDecl->getIsForwardProtoDecl())
       Diag(ProtocolLoc, diag::err_undef_protocolref,
 	   ProtoRefNames[i]->getName(),
@@ -995,13 +1009,12 @@
   
   for (unsigned i = 0; i != NumElts; ++i) {
     ObjcProtocolDecl *PDecl;
-    PDecl = Context.getObjCProtocolDecl(IdentList[i]);
+    PDecl = getObjCProtocolDecl(S, IdentList[i], AtProtocolLoc);
     if (!PDecl)  {// Already seen?
       PDecl = new ObjcProtocolDecl(SourceLocation(), 0, IdentList[i], true);
       // Chain & install the protocol decl into the identifier.
       PDecl->setNext(IdentList[i]->getFETokenInfo<ScopedDecl>());
       IdentList[i]->setFETokenInfo(PDecl);
-      Context.setObjCProtocolDecl(IdentList[i], PDecl);
     }
     // Remember that this needs to be removed when the scope is popped.
     S->AddDecl(IdentList[i]);
@@ -1019,18 +1032,8 @@
   ObjcCategoryDecl *CDecl;
   ObjcInterfaceDecl* IDecl = getObjCInterfaceDecl(S, ClassName, ClassLoc);
   CDecl = new ObjcCategoryDecl(AtInterfaceLoc, NumProtoRefs, ClassName);
-  if (IDecl) {
-    assert (ClassName->getFETokenInfo<ScopedDecl>() && "Missing @interface decl");
-    Decl *D = static_cast<Decl *>(ClassName->getFETokenInfo<ScopedDecl>());
-    assert(isa<ObjcInterfaceDecl>(D) && "Missing @interface decl");
-    
-    // Chain & install the category decl into the identifier.
-    // Note that head of the chain is the @interface class type and follow up
-    // nodes in the chain are the protocol decl nodes.
-    cast<ObjcInterfaceDecl>(D)->setNext(CDecl);
-  }
-  
   CDecl->setClassInterface(IDecl);
+
   /// Check that class of this category is already completely declared.
   if (!IDecl || IDecl->getIsForwardDecl())
     Diag(ClassLoc, diag::err_undef_interface, ClassName->getName());
@@ -1053,7 +1056,8 @@
   
   /// Check then save referenced protocols
   for (unsigned int i = 0; i != NumProtoRefs; i++) {
-    ObjcProtocolDecl* RefPDecl = Context.getObjCProtocolDecl(ProtoRefNames[i]);
+    ObjcProtocolDecl* RefPDecl = getObjCProtocolDecl(S, ProtoRefNames[i], 
+						     CategoryLoc);
     if (!RefPDecl || RefPDecl->getIsForwardProtoDecl())
       Diag(CategoryLoc, diag::err_undef_protocolref,
 	   ProtoRefNames[i]->getName(),
diff --git a/include/clang/AST/ASTContext.h b/include/clang/AST/ASTContext.h
index 59b1387..0258f98 100644
--- a/include/clang/AST/ASTContext.h
+++ b/include/clang/AST/ASTContext.h
@@ -39,7 +39,6 @@
   llvm::FoldingSet<FunctionTypeNoProto> FunctionTypeNoProtos;
   llvm::FoldingSet<FunctionTypeProto> FunctionTypeProtos;
   llvm::DenseMap<const RecordDecl*, const RecordLayout*> RecordLayoutInfo;
-  llvm::DenseMap<const IdentifierInfo*, ObjcProtocolDecl*> ProtocolNameInfo;
   llvm::SmallVector<ObjcImplementationDecl*, 8> ImplementationClassInfo;
   RecordDecl *CFConstantStringTypeDecl;
 public:
@@ -165,12 +164,6 @@
   /// position information.
   const RecordLayout &getRecordLayout(const RecordDecl *D, SourceLocation L);
   
-  ObjcProtocolDecl* getObjCProtocolDecl(const IdentifierInfo* ProtocolName) 
-  { return ProtocolNameInfo[ProtocolName]; }
-  void setObjCProtocolDecl(const IdentifierInfo* ProtocolName,
-                            ObjcProtocolDecl* ProtocolDecl)
-  { ProtocolNameInfo[ProtocolName] = ProtocolDecl; }
-  
   ObjcImplementationDecl* getObjcImplementationClass(unsigned ix) {
     return ImplementationClassInfo[ix];
   }
diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 2133d7a..98a3440 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -47,10 +47,13 @@
 
   /// IdentifierNamespace - According to C99 6.2.3, there are four namespaces,
   /// labels, tags, members and ordinary identifiers.
+  /// Objective-c protocols have their own namespace, so a protocol can have 
+  /// the same name as category, class, struct, typedef, etc.
   enum IdentifierNamespace {
     IDNS_Label,
     IDNS_Tag,
     IDNS_Member,
+    IDNS_Protocol,
     IDNS_Ordinary
   };
 private:
@@ -86,13 +89,14 @@
     case ParmVariable:
     case EnumConstant:
     case ObjcInterface:
-    case ObjcProtocol:
       return IDNS_Ordinary;
     case Struct:
     case Union:
     case Class:
     case Enum:
       return IDNS_Tag;
+    case ObjcProtocol:
+      return IDNS_Protocol;
     }
   }
   // global temp stats (until we have a per-module visitor)