Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt	(revision 199867)
+++ gcc/c-family/c.opt	(working copy)
@@ -661,6 +661,10 @@ Wselector
 ObjC ObjC++ Var(warn_selector) Warning
 Warn if a selector has multiple methods
 
+Wshadow-ivar
+ObjC ObjC++ Var(warn_shadow_ivar) Init(-1) Warning
+Warn if a local declaration hides an instance variable
+
 Wsequence-point
 C ObjC C++ ObjC++ Var(warn_sequence_point) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 Warn about possible violations of sequence point rules
@@ -1018,6 +1022,29 @@ fnil-receivers
 ObjC ObjC++ Var(flag_nil_receivers) Init(1)
 Assume that receivers of Objective-C messages may be nil
 
+flocal-ivars
+ObjC ObjC++ Var(flag_local_ivars) Init(1)
+Allow access to instance variables as if they were local declarations within instance method implementations.
+
+fivar-visibility=
+ObjC ObjC++ Joined RejectNegative Enum(ivar_visibility) Var(default_ivar_visibility) Init(IVAR_VISIBILITY_PROTECTED)
+-fvisibility=[private|protected|public|package]	Set the default symbol visibility
+
+Enum
+Name(ivar_visibility) Type(enum ivar_visibility) UnknownError(unrecognized ivar visibility value %qs)
+
+EnumValue
+Enum(ivar_visibility) String(private) Value(IVAR_VISIBILITY_PRIVATE)
+
+EnumValue
+Enum(ivar_visibility) String(protected) Value(IVAR_VISIBILITY_PROTECTED)
+
+EnumValue
+Enum(ivar_visibility) String(public) Value(IVAR_VISIBILITY_PUBLIC)
+
+EnumValue
+Enum(ivar_visibility) String(package) Value(IVAR_VISIBILITY_PACKAGE)
+
 fnonansi-builtins
 C++ ObjC++ Var(flag_no_nonansi_builtin, 0)
 
Index: gcc/flag-types.h
===================================================================
--- gcc/flag-types.h	(revision 199867)
+++ gcc/flag-types.h	(working copy)
@@ -104,6 +104,16 @@ enum symbol_visibility
 };
 #endif
 
+/* Enumerate Objective-c instance variable visibility settings. */
+
+enum ivar_visibility
+{
+  IVAR_VISIBILITY_PRIVATE,
+  IVAR_VISIBILITY_PROTECTED,
+  IVAR_VISIBILITY_PUBLIC,
+  IVAR_VISIBILITY_PACKAGE
+};
+
 /* The stack reuse level.  */
 enum stack_reuse_level
 {
Index: gcc/objc/objc-act.c
===================================================================
--- gcc/objc/objc-act.c	(revision 199867)
+++ gcc/objc/objc-act.c	(working copy)
@@ -223,7 +223,7 @@ struct imp_entry *imp_list = 0;
 int imp_count = 0;	/* `@implementation' */
 int cat_count = 0;	/* `@category' */
 
-objc_ivar_visibility_kind objc_ivar_visibility;
+objc_ivar_visibility_kind objc_ivar_visibility, objc_default_ivar_visibility;
 
 /* Use to generate method labels.  */
 static int method_slot = 0;
@@ -391,6 +391,22 @@ objc_init (void)
   if (!ok)
     return false;
 
+  /* Determine the default visibility for instance variables. */
+  switch (default_ivar_visibility)
+    {
+    case IVAR_VISIBILITY_PRIVATE:
+        objc_default_ivar_visibility = OBJC_IVAR_VIS_PRIVATE;
+        break;
+    case IVAR_VISIBILITY_PUBLIC:
+        objc_default_ivar_visibility = OBJC_IVAR_VIS_PUBLIC;
+        break;
+    case IVAR_VISIBILITY_PACKAGE:
+        objc_default_ivar_visibility = OBJC_IVAR_VIS_PACKAGE;
+        break;
+    default:
+        objc_default_ivar_visibility = OBJC_IVAR_VIS_PROTECTED;
+    }
+      
   /* Generate general types and push runtime-specific decls to file scope.  */
   synth_module_prologue ();
 
@@ -565,7 +581,7 @@ objc_start_class_interface (tree klass,
   objc_interface_context
     = objc_ivar_context
     = start_class (CLASS_INTERFACE_TYPE, klass, super_class, protos, attributes);
-  objc_ivar_visibility = OBJC_IVAR_VIS_PROTECTED;
+  objc_ivar_visibility = objc_default_ivar_visibility;
 }
 
 void
@@ -643,7 +659,7 @@ objc_start_class_implementation (tree kl
     = objc_ivar_context
     = start_class (CLASS_IMPLEMENTATION_TYPE, klass, super_class, NULL_TREE,
 		   NULL_TREE);
-  objc_ivar_visibility = OBJC_IVAR_VIS_PROTECTED;
+  objc_ivar_visibility = objc_default_ivar_visibility;
 }
 
 void
@@ -9360,6 +9376,12 @@ objc_lookup_ivar (tree other, tree id)
       && other && other != error_mark_node)
     return other;
 
+  /* Don't look up the ivar if the user has explicitly advised against
+   * it with -fno-local-ivars. */
+
+  if (!flag_local_ivars)
+    return other;
+
   /* Look up the ivar, but do not use it if it is not accessible.  */
   ivar = is_ivar (objc_ivar_chain, id);
 
@@ -9376,8 +9398,11 @@ objc_lookup_ivar (tree other, tree id)
       && !DECL_FILE_SCOPE_P (other))
 #endif
     {
-      warning (0, "local declaration of %qE hides instance variable", id);
-
+      if (warn_shadow_ivar == 1 || (warn_shadow && warn_shadow_ivar != 0)) {
+          warning (warn_shadow_ivar ? OPT_Wshadow_ivar : OPT_Wshadow,
+                   "local declaration of %qE hides instance variable", id);
+      }
+        
       return other;
     }