diff --git a/bin/uglifyjs b/bin/uglifyjs
index 34ed80eb..71bddbc0 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -45,6 +45,9 @@ out: while (args.length > 0) {
     var v = args.shift();
     switch (v) {
       case "-b":
+      case "--unique_ids":
+        options.unique_ids = true;
+        break;
       case "--beautify":
         options.codegen_options.beautify = true;
         break;
@@ -296,7 +299,8 @@ function squeeze_it(code) {
                 toplevel     : options.mangle_toplevel,
                 defines      : options.defines,
                 except       : options.reserved_names,
-                no_functions : options.no_mangle_functions
+                no_functions : options.no_mangle_functions,
+                unique_ids   : options.unique_ids
             });
         });
         if (options.squeeze) ast = time_it("squeeze", function(){
diff --git a/lib/process.js b/lib/process.js
index a461bd7a..0919c971 100644
--- a/lib/process.js
+++ b/lib/process.js
@@ -270,6 +270,7 @@ function ast_walker() {
 };
 
 /* -----[ Scope and mangling ]----- */
+mangled_id = 0;    // for unique mangled names
 
 function Scope(parent) {
     this.names = {};        // names defined in this scope
@@ -329,7 +330,7 @@ Scope.prototype = {
         };
     },
 
-    next_mangled: function() {
+    next_mangled: function(unique_ids) {
         // we must be careful that the new mangled name:
         //
         // 1. doesn't shadow a mangled name from a parent
@@ -364,6 +365,8 @@ Scope.prototype = {
             // I got "do" once. :-/
             if (!is_identifier(m))
                 continue;
+            if (unique_ids)
+                return m + mangled_id++;
 
             return m;
         }
@@ -372,13 +375,13 @@ Scope.prototype = {
         this.rev_mangled[m] = name;
         return this.mangled[name] = m;
     },
-    get_mangled: function(name, newMangle) {
+    get_mangled: function(name, newMangle, unique_ids) {
         if (this.uses_eval || this.uses_with) return name; // no mangle if eval or with is in use
         var s = this.has(name);
         if (!s) return name; // not in visible scope, no mangle
         if (HOP(s.mangled, name)) return s.mangled[name]; // already mangled in this scope
         if (!newMangle) return name;                      // not found and no mangling requested
-        return s.set_mangle(name, s.next_mangled());
+        return s.set_mangle(name, s.next_mangled(unique_ids));
     },
     references: function(name) {
         return name && !this.parent || this.uses_with || this.uses_eval || this.refs[name];
@@ -516,7 +519,8 @@ function ast_mangle(ast, options) {
         toplevel     : false,
         defines      : null,
         except       : null,
-        no_functions : false
+        no_functions : false,
+        unique_ids   : false
     });
 
     function get_mangled(name, newMangle) {
@@ -527,7 +531,7 @@ function ast_mangle(ast, options) {
         if (options.no_functions && HOP(scope.names, name) &&
             (scope.names[name] == 'defun' || scope.names[name] == 'lambda'))
             return name;
-        return scope.get_mangled(name, newMangle);
+        return scope.get_mangled(name, newMangle, options.unique_ids);
     };
 
     function get_define(name) {