diff --git a/include/clang-c/Index.h b/include/clang-c/Index.h
index de2b5d6898..1b9ba4c4f7 100644
--- a/include/clang-c/Index.h
+++ b/include/clang-c/Index.h
@@ -104,8 +104,11 @@ CXTranslationUnit clang_createTranslationUnit(
      clang_loadTranslationUnit(CXTranslationUnit, printObjCInterfaceNames);
    }
 */
-typedef void (*CXTranslationUnitIterator)(CXTranslationUnit, CXCursor);
-void clang_loadTranslationUnit(CXTranslationUnit, CXTranslationUnitIterator);
+typedef void *CXClientData;
+typedef void (*CXTranslationUnitIterator)(CXTranslationUnit, CXCursor, 
+                                          CXClientData);
+void clang_loadTranslationUnit(CXTranslationUnit, CXTranslationUnitIterator,
+                               CXClientData);
 
 /*
    Usage: clang_loadDeclaration(). Will load the declaration, issuing a 
diff --git a/tools/CIndex/CIndex.cpp b/tools/CIndex/CIndex.cpp
index f8d223a510..9577391288 100644
--- a/tools/CIndex/CIndex.cpp
+++ b/tools/CIndex/CIndex.cpp
@@ -28,9 +28,16 @@ namespace {
 class TUVisitor : public DeclVisitor<TUVisitor> {
   CXTranslationUnit TUnit;
   CXTranslationUnitIterator Callback;
+  CXClientData CData;
+  
+  void Call(enum CXCursorKind CK, NamedDecl *ND) {
+    CXCursor C = { CK, ND };
+    Callback(TUnit, C, CData);
+  }
 public:
-  TUVisitor(CXTranslationUnit CTU, CXTranslationUnitIterator cback) : 
-    TUnit(CTU), Callback(cback) {}
+  TUVisitor(CXTranslationUnit CTU, 
+            CXTranslationUnitIterator cback, CXClientData D) : 
+    TUnit(CTU), Callback(cback), CData(D) {}
   
   void VisitTranslationUnitDecl(TranslationUnitDecl *D) {
     VisitDeclContext(dyn_cast<DeclContext>(D));
@@ -40,29 +47,23 @@ public:
            I = DC->decls_begin(), E = DC->decls_end(); I != E; ++I)
       Visit(*I);
   }
-  void VisitTypedefDecl(TypedefDecl *ND) {
-    CXCursor C = { CXCursor_TypedefDecl, ND };
-    Callback(TUnit, C);
+  void VisitTypedefDecl(TypedefDecl *ND) { 
+    Call(CXCursor_TypedefDecl, ND); 
   }
   void VisitTagDecl(TagDecl *ND) {
-    CXCursor C = { ND->isEnum() ? CXCursor_EnumDecl : CXCursor_RecordDecl, ND };
-    Callback(TUnit, C);
+    Call(ND->isEnum() ? CXCursor_EnumDecl : CXCursor_RecordDecl, ND);
   }
   void VisitFunctionDecl(FunctionDecl *ND) {
-    CXCursor C = { CXCursor_FunctionDecl, ND };
-    Callback(TUnit, C);
+    Call(CXCursor_FunctionDecl, ND);
   }
   void VisitObjCInterfaceDecl(ObjCInterfaceDecl *ND) {
-    CXCursor C = { CXCursor_ObjCInterfaceDecl, ND };
-    Callback(TUnit, C);
+    Call(CXCursor_ObjCInterfaceDecl, ND);
   }
   void VisitObjCCategoryDecl(ObjCCategoryDecl *ND) {
-    CXCursor C = { CXCursor_ObjCCategoryDecl, ND };
-    Callback(TUnit, C);
+    Call(CXCursor_ObjCCategoryDecl, ND);
   }
   void VisitObjCProtocolDecl(ObjCProtocolDecl *ND) {
-    CXCursor C = { CXCursor_ObjCProtocolDecl, ND };
-    Callback(TUnit, C);
+    Call(CXCursor_ObjCProtocolDecl, ND);
   }
 };
 
@@ -105,13 +106,14 @@ CXTranslationUnit clang_createTranslationUnit(
 
 
 void clang_loadTranslationUnit(
-  CXTranslationUnit CTUnit, CXTranslationUnitIterator callback)
+  CXTranslationUnit CTUnit, CXTranslationUnitIterator callback,
+  CXClientData CData)
 {
   assert(CTUnit && "Passed null CXTranslationUnit");
   ASTUnit *CXXUnit = static_cast<ASTUnit *>(CTUnit);
   ASTContext &Ctx = CXXUnit->getASTContext();
   
-  TUVisitor DVisit(CTUnit, callback);
+  TUVisitor DVisit(CTUnit, callback, CData);
   DVisit.Visit(Ctx.getTranslationUnitDecl());
 }
 
diff --git a/tools/c-index-test/c-index-test.c b/tools/c-index-test/c-index-test.c
index 1ef8e924bc..30700d8ae3 100644
--- a/tools/c-index-test/c-index-test.c
+++ b/tools/c-index-test/c-index-test.c
@@ -1,14 +1,18 @@
+/* c-index-test.c */
 
 #include "clang-c/Index.h"
 #include <stdio.h>
 
-static void PrintDecls(CXTranslationUnit Unit, CXCursor Cursor) {
+static void PrintDecls(CXTranslationUnit Unit, CXCursor Cursor,
+                       CXClientData Filter) {
   if (clang_isDeclaration(Cursor.kind)) {
-    printf("%s => %s", clang_getKindSpelling(Cursor.kind),
-                       clang_getDeclSpelling(Cursor.decl));
-    printf(" (%s,%d:%d)\n", clang_getCursorSource(Cursor),
-                            clang_getCursorLine(Cursor),
-                            clang_getCursorColumn(Cursor));
+    if (Cursor.kind == *(enum CXCursorKind *)Filter) {
+      printf("%s => %s", clang_getKindSpelling(Cursor.kind),
+                         clang_getDeclSpelling(Cursor.decl));
+      printf(" (%s,%d:%d)\n", clang_getCursorSource(Cursor),
+                              clang_getCursorLine(Cursor),
+                              clang_getCursorColumn(Cursor));
+    }
   }
 }
 
@@ -18,6 +22,9 @@ static void PrintDecls(CXTranslationUnit Unit, CXCursor Cursor) {
 int main(int argc, char **argv) {
   CXIndex Idx = clang_createIndex();
   CXTranslationUnit TU = clang_createTranslationUnit(Idx, argv[1]);
-  clang_loadTranslationUnit(TU, PrintDecls);
+  
+  /* Use client data to only print ObjC interfaces */
+  enum CXCursorKind filterData = CXCursor_ObjCInterfaceDecl;
+  clang_loadTranslationUnit(TU, PrintDecls, &filterData);
   return 1;
 }