diff --git a/README.md b/README.md
index a19f7ef4..9c63d727 100644
--- a/README.md
+++ b/README.md
@@ -133,7 +133,11 @@ The available options are:
   --reserved-file               File containing reserved names
   --reserve-domprops            Make (most?) DOM properties reserved for
                                 --mangle-props
-  --mangle-props                Mangle property names
+  --mangle-props                Mangle property names (default `0`). Set to 
+                                `true` or `1` to mangle all property names. Set
+                                to `1` to only mangle unquoted property names.
+                                Use the `keep_quoted_props` beautifier option to
+                                preserve the quotes around property names.
   --mangle-regex                Only mangle property names matching the regex
   --name-cache                  File to hold mangled names mappings
   --pure-funcs                  List of functions that can be safely removed if
diff --git a/bin/uglifyjs b/bin/uglifyjs
index 45c92b50..ec791b07 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -69,7 +69,7 @@ You need to pass an argument to this option to specify the name that your module
     .describe("quotes", "Quote style (0 - auto, 1 - single, 2 - double, 3 - original)")
     .describe("reserved-file", "File containing reserved names")
     .describe("reserve-domprops", "Make (most?) DOM properties reserved for --mangle-props")
-    .describe("mangle-props", "Mangle property names")
+    .describe("mangle-props", "Mangle property names (0 - disabled, 1 - mangle all properties, 2 - mangle unquoted properies)")
     .describe("mangle-regex", "Only mangle property names matching the regex")
     .describe("name-cache", "File to hold mangled names mappings")
     .describe("pure-funcs", "List of functions that can be safely removed if their return value is not used")
@@ -125,7 +125,6 @@ You need to pass an argument to this option to specify the name that your module
     .boolean("noerr")
     .boolean("bare-returns")
     .boolean("keep-fnames")
-    .boolean("mangle-props")
     .boolean("reserve-domprops")
 
     .wrap(80)
@@ -388,6 +387,10 @@ async.eachLimit(files, 1, function (file, cb) {
         TOPLEVEL = TOPLEVEL.wrap_enclose(arg_parameter_list);
     }
 
+    if (ARGS.mangle_props === true) {
+        ARGS.mangle_props = 1;
+    }
+
     if (ARGS.mangle_props || ARGS.name_cache) (function(){
         var reserved = RESERVED ? RESERVED.props : null;
         var cache = readNameCache("props");
@@ -401,10 +404,11 @@ async.eachLimit(files, 1, function (file, cb) {
         }
 
         TOPLEVEL = UglifyJS.mangle_properties(TOPLEVEL, {
-            reserved   : reserved,
-            cache      : cache,
-            only_cache : !ARGS.mangle_props,
-            regex      : regex
+            reserved      : reserved,
+            cache         : cache,
+            only_cache    : !ARGS.mangle_props,
+            regex         : regex,
+            ignore_quoted : ARGS.mangle_props == 2
         });
         writeNameCache("props", cache);
     })();
diff --git a/lib/propmangle.js b/lib/propmangle.js
index 840bda91..c905e85e 100644
--- a/lib/propmangle.js
+++ b/lib/propmangle.js
@@ -65,7 +65,8 @@ function mangle_properties(ast, options) {
         reserved : null,
         cache : null,
         only_cache : false,
-        regex : null
+        regex : null,
+        ignore_quoted : false
     });
 
     var reserved = options.reserved;
@@ -81,6 +82,7 @@ function mangle_properties(ast, options) {
     }
 
     var regex = options.regex;
+    var ignore_quoted = options.ignore_quoted;
 
     var names_to_mangle = [];
     var unmangleable = [];
@@ -88,11 +90,13 @@ function mangle_properties(ast, options) {
     // step 1: find candidates to mangle
     ast.walk(new TreeWalker(function(node){
         if (node instanceof AST_ObjectKeyVal) {
-            add(node.key);
+            if (!(ignore_quoted && node.quote))
+                add(node.key);
         }
         else if (node instanceof AST_ObjectProperty) {
             // setter or getter, since KeyVal is handled above
-            add(node.key.name);
+            if (!(ignore_quoted && node.key.quote))
+                add(node.key.name);
         }
         else if (node instanceof AST_Dot) {
             if (this.parent() instanceof AST_Assign) {
@@ -101,7 +105,8 @@ function mangle_properties(ast, options) {
         }
         else if (node instanceof AST_Sub) {
             if (this.parent() instanceof AST_Assign) {
-                addStrings(node.property);
+                if (!(ignore_quoted && node.property.quote))
+                    addStrings(node.property);
             }
         }
     }));
diff --git a/test/compress/properties.js b/test/compress/properties.js
index 39470738..c903d315 100644
--- a/test/compress/properties.js
+++ b/test/compress/properties.js
@@ -72,3 +72,35 @@ evaluate_length: {
         a = ("foo" + b).length;
     }
 }
+
+mangle_properties: {
+    mangle_props = {
+        ignore_quoted: false
+    };
+    input: {
+        a["foo"] = "bar";
+        a.color = "red";
+        x = {"bar": 10};
+    }
+    expect: {
+        a["a"] = "bar";
+        a.b = "red";
+        x = {c: 10};
+    }
+}
+
+mangle_unquoted_properties: {
+    mangle_props = {
+        ignore_quoted: true
+    };
+    input: {
+        a["foo"] = "bar";
+        a.color = "red";
+        x = {"bar": 10};
+    }
+    expect: {
+        a["foo"] = "bar";
+        a.a = "red";
+        x = {"bar": 10};
+    }
+}