diff --git a/browser/installer/removed-files.in b/browser/installer/removed-files.in
index 4bf016300f3..0ea7e669ef7 100644
--- a/browser/installer/removed-files.in
+++ b/browser/installer/removed-files.in
@@ -584,6 +584,7 @@ components/nsXmlRpcClient.js
 components/nsInterfaceInfoToIDL.js
 components/nsScriptableIO.js
 chrome/chromelist.txt
+modules/JSON.jsm
 #ifdef XP_MACOSX
 LICENSE
 extensions/inspector@mozilla.org/chrome/chromelist.txt
diff --git a/js/src/xpconnect/loader/JSON.jsm b/js/src/xpconnect/loader/JSON.jsm
deleted file mode 100644
index 639f8749ffb..00000000000
--- a/js/src/xpconnect/loader/JSON.jsm
+++ /dev/null
@@ -1,178 +0,0 @@
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is Mozilla code.
- *
- * The Initial Developer of the Original Code is
- * Simon Bünzli <zeniko@gmail.com>
- * Portions created by the Initial Developer are Copyright (C) 2006-2007
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-/**
- * Utilities for JavaScript code to handle JSON content.
- * See http://www.json.org/ for comprehensive information about JSON.
- *
- * Import this module through
- *
- * Components.utils.import("resource://gre/modules/JSON.jsm");
- *
- * Usage:
- *
- * var newJSONString = JSONModule.toString( GIVEN_JAVASCRIPT_OBJECT );
- * var newJavaScriptObject = JSONModule.fromString( GIVEN_JSON_STRING );
- *
- * Note: For your own safety, Objects/Arrays returned by
- *       JSONModule.fromString aren't instanceof Object/Array.
- */
-
-var EXPORTED_SYMBOLS = ["JSONModule"];
-
-// The following code is a loose adaption of Douglas Crockford's code
-// from http://www.json.org/json.js (public domain'd)
-
-// Notable differences:
-// * Unserializable values such as |undefined| or functions aren't
-//   silently dropped but always lead to a TypeError.
-// * An optional key blacklist has been added to JSON.toString
-
-var JSONModule = {
-  /**
-   * Converts a JavaScript object into a JSON string.
-   *
-   * @param aJSObject is the object to be converted
-   * @param aKeysToDrop is an optional array of keys which will be
-   *                    ignored in all objects during the serialization
-   * @return the object's JSON representation
-   *
-   * Note: aJSObject MUST not contain cyclic references.
-   */
-  toString: function JSON_toString(aJSObject, aKeysToDrop) {
-    // we use a single string builder for efficiency reasons
-    var pieces = [];
-    
-    // this recursive function walks through all objects and appends their
-    // JSON representation (in one or several pieces) to the string builder
-    function append_piece(aObj) {
-      if (typeof aObj == "string") {
-        aObj = aObj.replace(/[\\"\x00-\x1F\u0080-\uFFFF]/g, function($0) {
-          // use the special escape notation if one exists, otherwise
-          // produce a general unicode escape sequence
-          switch ($0) {
-          case "\b": return "\\b";
-          case "\t": return "\\t";
-          case "\n": return "\\n";
-          case "\f": return "\\f";
-          case "\r": return "\\r";
-          case '"':  return '\\"';
-          case "\\": return "\\\\";
-          }
-          return "\\u" + ("0000" + $0.charCodeAt(0).toString(16)).slice(-4);
-        });
-        pieces.push('"' + aObj + '"')
-      }
-      else if (typeof aObj == "boolean") {
-        pieces.push(aObj ? "true" : "false");
-      }
-      else if (typeof aObj == "number" && isFinite(aObj)) {
-        // there is no representation for infinite numbers or for NaN!
-        pieces.push(aObj.toString());
-      }
-      else if (aObj === null) {
-        pieces.push("null");
-      }
-      // if it looks like an array, treat it as such - this is required
-      // for all arrays from either outside this module or a sandbox
-      else if (aObj instanceof Array ||
-               typeof aObj == "object" && "length" in aObj &&
-               (aObj.length === 0 || aObj[aObj.length - 1] !== undefined)) {
-        pieces.push("[");
-        for (var i = 0; i < aObj.length; i++) {
-          arguments.callee(aObj[i]);
-          pieces.push(",");
-        }
-        if (aObj.length > 0)
-          pieces.pop(); // drop the trailing colon
-        pieces.push("]");
-      }
-      else if (typeof aObj == "object") {
-        pieces.push("{");
-        for (var key in aObj) {
-          // allow callers to pass objects containing private data which
-          // they don't want the JSON string to contain (so they don't
-          // have to manually pre-process the object)
-          if (aKeysToDrop && aKeysToDrop.indexOf(key) != -1)
-            continue;
-          
-          arguments.callee(key.toString());
-          pieces.push(":");
-          arguments.callee(aObj[key]);
-          pieces.push(",");
-        }
-        if (pieces[pieces.length - 1] == ",")
-          pieces.pop(); // drop the trailing colon
-        pieces.push("}");
-      }
-      else {
-        throw new TypeError("No JSON representation for this object!");
-      }
-    }
-    append_piece(aJSObject);
-    
-    return pieces.join("");
-  },
-
-  /**
-   * Converts a JSON string into a JavaScript object.
-   *
-   * @param aJSONString is the string to be converted
-   * @return a JavaScript object for the given JSON representation
-   */
-  fromString: function JSON_fromString(aJSONString) {
-    if (!this.isMostlyHarmless(aJSONString))
-      throw new SyntaxError("No valid JSON string!");
-    
-    var s = new Components.utils.Sandbox("about:blank");
-    return Components.utils.evalInSandbox("(" + aJSONString + ")", s);
-  },
-
-  /**
-   * Checks whether the given string contains potentially harmful
-   * content which might be executed during its evaluation
-   * (no parser, thus not 100% safe! Best to use a Sandbox for evaluation)
-   *
-   * @param aString is the string to be tested
-   * @return a boolean
-   */
-  isMostlyHarmless: function JSON_isMostlyHarmless(aString) {
-    const maybeHarmful = /[^,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]/;
-    const jsonStrings = /"(\\.|[^"\\\n\r])*"/g;
-    
-    return !maybeHarmful.test(aString.replace(jsonStrings, ""));
-  }
-};
diff --git a/js/src/xpconnect/loader/Makefile.in b/js/src/xpconnect/loader/Makefile.in
index 6c5a93fd50f..3b6837c7800 100644
--- a/js/src/xpconnect/loader/Makefile.in
+++ b/js/src/xpconnect/loader/Makefile.in
@@ -56,7 +56,7 @@ REQUIRES	= xpcom \
 
 CPPSRCS		= mozJSComponentLoader.cpp mozJSSubScriptLoader.cpp
 
-EXTRA_JS_MODULES = XPCOMUtils.jsm JSON.jsm ISO8601DateUtils.jsm
+EXTRA_JS_MODULES = XPCOMUtils.jsm ISO8601DateUtils.jsm
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/js/src/xpconnect/tests/unit/test_json.js b/js/src/xpconnect/tests/unit/test_json.js
deleted file mode 100644
index 56744b41958..00000000000
--- a/js/src/xpconnect/tests/unit/test_json.js
+++ /dev/null
@@ -1,131 +0,0 @@
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is mozilla.org code.
- *
- * The Initial Developer of the Original Code is
- * Simon Bünzli <zeniko@gmail.com>
- * Portions created by the Initial Developer are Copyright (C) 2007
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-function run_test() {
-  // converts an object to a JSON string and tests its integrity
-  function toJSONString(a) {
-    var res = JSONModule.toString(a);
-    if (!JSONModule.isMostlyHarmless(res))
-      throw new SyntaxError("Invalid JSON string: " + res);
-    return res;
-  }
-  
-  // ensures that an object can't be converted to a JSON string
-  function isInvalidType(a) {
-    try {
-      JSONModule.toString(a);
-      return false;
-    } catch (ex) {
-      return ex.name == "TypeError";
-    }
-  }
-  // ensures that a string can't be converted back to a JavaScript object
-  function isInvalidSyntax(a) {
-    try {
-      JSONModule.fromString(a);
-      return false;
-    } catch (ex) {
-      return ex.name == "SyntaxError";
-    }
-  }
-  
-  Components.utils.import("resource://gre/modules/JSON.jsm");
-  do_check_eq(typeof(JSONModule), "object");
-  
-  // some of the tests are adapted from /testing/mochitest/tests/test_Base.js
-  do_check_eq(toJSONString(true), "true");
-  do_check_eq(toJSONString(false), "false");
-  
-  do_check_eq(toJSONString(1), "1");
-  do_check_eq(toJSONString(1.23), "1.23");
-  do_check_eq(toJSONString(1.23e-45), "1.23e-45");
-  
-  do_check_true(isInvalidType(Infinity));
-  do_check_true(isInvalidType(NaN));
-  
-  //XXXzeniko: using € instead of \u20ac fails because of encoding issues
-  do_check_eq(toJSONString("Foo-Bar \b\t\n\f\r\"\\ \x01\u20ac"),
-              '"Foo-Bar \\b\\t\\n\\f\\r\\"\\\\ \\u0001\\u20ac"');
-  
-  do_check_eq(toJSONString(null), "null");
-  do_check_true(isInvalidType(undefined));
-  
-  do_check_eq(toJSONString([1, "2", 3.3]), '[1,"2",3.3]');
-  // duck-typed Array (since we'll never really get something instanceof Array)
-  do_check_eq(toJSONString({ 0: 0, 1: "1", 2: -2.2, length: 3 }), '[0,"1",-2.2]');
-  
-  var obj = { a: 1, b: "2", c: [-3e+30] };
-  do_check_eq(toJSONString(obj), '{"a":1,"b":"2","c":[-3e+30]}');
-  do_check_eq(JSONModule.toString(obj, ["b", "c"] /* keys to drop */), '{"a":1}');
-  
-  do_check_true(isInvalidType(function() { }));
-  
-  // make sure that toJSONString actually works...
-  do_check_eq(toJSONString(obj), JSONModule.toString(obj));
-  
-  do_check_eq(JSONModule.fromString("true"), true);
-  do_check_eq(JSONModule.fromString("false"), false);
-  do_check_eq(JSONModule.fromString("1"), 1);
-  do_check_eq(JSONModule.fromString('"2.2"'), "2.2");
-  do_check_eq(JSONModule.fromString("1.23e-45"), 1.23e-45);
-  do_check_true(isInvalidSyntax("NaN"));
-  
-  do_check_eq(JSONModule.fromString('"Foo-Bar \\b\\t\\n\\f\\r\\"\\\\ \\u0001\\u20ac"'),
-                              "Foo-Bar \b\t\n\f\r\"\\ \x01\u20ac");
-  do_check_true(isInvalidSyntax('"multi\nline"'));
-  do_check_eq(JSONModule.fromString("null"), null);
-  do_check_true(isInvalidSyntax("."));
-  
-  var res = JSONModule.fromString('[1,"2",3.3]');
-  do_check_eq(res.length, 3);
-  do_check_eq(res[2], 3.3);
-  // res is an instance of the sandbox's array
-  do_check_false(res instanceof Array);
-  
-  res = JSONModule.fromString(toJSONString(obj));
-  do_check_eq(res.a, obj.a);
-  do_check_eq(res.b, obj.b);
-  do_check_eq(res.c.length, obj.c.length);
-  do_check_eq(res.c[0], obj.c[0]);
-  
-  // those would throw on JSONModule.fromString if there's no object |a|
-  do_check_true(JSONModule.isMostlyHarmless("a"));
-  do_check_true(JSONModule.isMostlyHarmless("a[0]"));
-  do_check_true(JSONModule.isMostlyHarmless('a["alert(\\"P0wn3d!\\");"]'));
-  
-  do_check_false(JSONModule.isMostlyHarmless('(function() { alert("P0wn3d!"); })()'));
-  do_check_false(JSONModule.isMostlyHarmless('{ get a() { return "P0wn3d!"; } }'));
-}