Index: cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td
===================================================================
--- cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td
+++ cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td
@@ -13,12 +13,31 @@
 // Packages.
 //===----------------------------------------------------------------------===//
 
+// The Alpha package is for checkers that have too many false positives to be
+// turned on by default. The hierarchy under Alpha should be organized in the
+// hierarchy checkers would have had if they were truly at the top level.
+// (For example, a Cocoa-specific checker that is alpha should be in
+// alpha.osx.cocoa).
 def Alpha : Package<"alpha">;
 
 def Core : Package<"core">;
 def CoreBuiltin : Package<"builtin">, InPackage<Core>;
 def CoreUninitialized  : Package<"uninitialized">, InPackage<Core>;
 def CoreAlpha : Package<"core">, InPackage<Alpha>, Hidden;
+
+// The OptIn package is for checkers that are not alpha and that would normally
+// be on by default but where the driver does not have enough information to
+// determine when they are applicable. For example, localizability checkers fit
+// this criterion because the driver cannot determine whether a project is
+// localized or not -- this is best determined at the IDE or build-system level.
+//
+// The checker hierarchy under OptIn should mirror that in Alpha: checkers
+// should be organized as if they were at the top level.
+//
+// Note: OptIn is *not* intended for checkers that are too noisy to be on by
+// default. Such checkers belong in the alpha package.
+def OptIn : Package<"optin">;
+
 def Nullability : Package<"nullability">;
 
 def Cplusplus : Package<"cplusplus">;
@@ -39,11 +58,18 @@
 
 def OSX : Package<"osx">;
 def OSXAlpha : Package<"osx">, InPackage<Alpha>, Hidden;
+def OSXOptIn : Package<"osx">, InPackage<OptIn>;
+
 def Cocoa : Package<"cocoa">, InPackage<OSX>;
 def CocoaAlpha : Package<"cocoa">, InPackage<OSXAlpha>, Hidden;
+def CocoaOptIn : Package<"cocoa">, InPackage<OSXOptIn>;
+
 def CoreFoundation : Package<"coreFoundation">, InPackage<OSX>;
 def Containers : Package<"containers">, InPackage<CoreFoundation>;
 
+def LocalizabilityAlpha : Package<"localizability">, InPackage<CocoaAlpha>;
+def LocalizabilityOptIn : Package<"localizability">, InPackage<CocoaOptIn>;
+
 def LLVM : Package<"llvm">;
 def Debug : Package<"debug">;
 
@@ -485,18 +511,6 @@
   HelpText<"Check for direct assignments to instance variables in the methods annotated with objc_no_direct_instance_variable_assignment">,
   DescFile<"DirectIvarAssignment.cpp">;
 
-def NonLocalizedStringChecker : Checker<"NonLocalizedStringChecker">,
-  HelpText<"Warns about uses of non-localized NSStrings passed to UI methods expecting localized NSStrings">,
-  DescFile<"LocalizationChecker.cpp">;
-
-def EmptyLocalizationContextChecker : Checker<"EmptyLocalizationContextChecker">,
-  HelpText<"Check that NSLocalizedString macros include a comment for context">,
-  DescFile<"LocalizationChecker.cpp">;
-
-def PluralMisuseChecker : Checker<"PluralMisuseChecker">,
-  HelpText<"Warns against using one vs. many plural pattern in code when generating localized strings.">,
-  DescFile<"LocalizationChecker.cpp">;
-
 } // end "alpha.osx.cocoa"
 
 let ParentPackage = CoreFoundation in {
@@ -524,6 +538,23 @@
   DescFile<"ObjCContainersChecker.cpp">;
 
 }
+
+let ParentPackage = LocalizabilityOptIn in {
+def NonLocalizedStringChecker : Checker<"NonLocalizedStringChecker">,
+  HelpText<"Warns about uses of non-localized NSStrings passed to UI methods expecting localized NSStrings">,
+  DescFile<"LocalizationChecker.cpp">;
+
+def EmptyLocalizationContextChecker : Checker<"EmptyLocalizationContextChecker">,
+  HelpText<"Check that NSLocalizedString macros include a comment for context">,
+  DescFile<"LocalizationChecker.cpp">;
+}
+
+let ParentPackage = LocalizabilityAlpha in {
+def PluralMisuseChecker : Checker<"PluralMisuseChecker">,
+  HelpText<"Warns against using one vs. many plural pattern in code when generating localized strings.">,
+  DescFile<"LocalizationChecker.cpp">;
+}
+
 //===----------------------------------------------------------------------===//
 // Checkers for LLVM development.
 //===----------------------------------------------------------------------===//
Index: cfe/trunk/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
===================================================================
--- cfe/trunk/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
+++ cfe/trunk/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
@@ -1198,4 +1198,4 @@
 
 void ento::registerPluralMisuseChecker(CheckerManager &mgr) {
   mgr.registerChecker<PluralMisuseChecker>();
-}
\ No newline at end of file
+}
Index: cfe/trunk/test/Analysis/localization-aggressive.m
===================================================================
--- cfe/trunk/test/Analysis/localization-aggressive.m
+++ cfe/trunk/test/Analysis/localization-aggressive.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -analyze -fblocks -analyzer-store=region  -analyzer-checker=alpha.osx.cocoa.NonLocalizedStringChecker -analyzer-checker=alpha.osx.cocoa.EmptyLocalizationContextChecker -verify  -analyzer-config AggressiveReport=true %s
+// RUN: %clang_cc1 -analyze -fblocks -analyzer-store=region  -analyzer-checker=optin.osx.cocoa.localizability.NonLocalizedStringChecker -analyzer-checker=optin.osx.cocoa.localizability.EmptyLocalizationContextChecker -verify  -analyzer-config AggressiveReport=true %s
 
 // These declarations were reduced using Delta-Debugging from Foundation.h
 // on Mac OS X.
Index: cfe/trunk/test/Analysis/localization.m
===================================================================
--- cfe/trunk/test/Analysis/localization.m
+++ cfe/trunk/test/Analysis/localization.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -analyze -fblocks -analyzer-store=region -analyzer-checker=alpha.osx.cocoa.NonLocalizedStringChecker -analyzer-checker=alpha.osx.cocoa.PluralMisuseChecker -verify  %s
+// RUN: %clang_cc1 -analyze -fblocks -analyzer-store=region -analyzer-checker=optin.osx.cocoa.localizability.NonLocalizedStringChecker -analyzer-checker=alpha.osx.cocoa.localizability.PluralMisuseChecker -verify  %s
 
 // The larger set of tests in located in localization.m. These are tests
 // specific for non-aggressive reporting.