diff --git a/build.js b/build.js
index 156fd14a3..0f8c7e419 100755
--- a/build.js
+++ b/build.js
@@ -150,7 +150,7 @@
     'bind': [],
     'bindAll': ['bind', 'functions'],
     'chain': ['mixin'],
-    'clone': ['extend', 'isArray'],
+    'clone': ['extend', 'forOwn', 'isArguments'],
     'compact': [],
     'compose': [],
     'contains': [],
@@ -774,17 +774,12 @@
 
     // build replacement code
     lodash.forOwn({
-      'Arguments': 'argsClass',
       'Date': 'dateClass',
       'Function': 'funcClass',
       'Number': 'numberClass',
       'RegExp': 'regexpClass',
       'String': 'stringClass'
     }, function(value, key) {
-      // skip `isArguments` if not a mobile build
-      if (!isMobile && key == 'Arguments') {
-        return;
-      }
       var funcName = 'is' + key,
           funcCode = matchFunction(source, funcName);
 
@@ -887,15 +882,19 @@
     // remove IE `shift` and `splice` fix from mutator Array functions mixin
     source = source.replace(/(?:\s*\/\/.*)*\n( +)if *\(value.length *=== *0[\s\S]+?\n\1}/, '');
 
-    // remove `noCharByIndex` from `_.reduceRight`
-    source = source.replace(/noCharByIndex *&&[^:]+: *([^;]+)/g, '$1');
+    // remove `noArgsClass` from `_.clone` and `_.size`
+    source = source.replace(/ *\|\| *\(noArgsClass *&[^)]+?\)\)/g, '');
 
     // remove `noArraySliceOnStrings` from `_.toArray`
     source = source.replace(/noArraySliceOnStrings *\?[^:]+: *([^)]+)/g, '$1');
 
+    // remove `noCharByIndex` from `_.reduceRight`
+    source = source.replace(/noCharByIndex *&&[^:]+: *([^;]+)/g, '$1');
+
     source = removeVar(source, 'extendIteratorOptions');
     source = removeVar(source, 'hasDontEnumBug');
     source = removeVar(source, 'iteratorTemplate');
+    source = removeVar(source, 'noArgsClass');
     source = removeVar(source, 'noArraySliceOnStrings');
     source = removeVar(source, 'noCharByIndex');
     source = removeIsArgumentsFallback(source);
diff --git a/build/pre-compile.js b/build/pre-compile.js
index d488c0dfe..fe6ee0f96 100644
--- a/build/pre-compile.js
+++ b/build/pre-compile.js
@@ -220,6 +220,13 @@
     // Closure Compiler errors trying to minify them
     source = source.replace(/(arrayLikeClasses =)[\s\S]+?= *true/g, "$1{'[object Arguments]': true, '[object Array]': true, '[object String]': true }");
 
+    // manually convert `cloneableClasses` property assignments because
+    // Closure Compiler errors trying to minify them
+    source = source.replace(/(cloneableClasses =)[\s\S]+?= *true/g,
+      "$1{'[object Array]': true, '[object Boolean]': true, '[object Date]': true, " +
+      "'[object Number]': true, '[object Object]': true, '[object RegExp]': true, '[object String]': true }"
+    );
+
     // add brackets to whitelisted properties so Closure Compiler won't mung them
     // http://code.google.com/closure/compiler/docs/api-tutorial3.html#export
     source = source.replace(RegExp('\\.(' + propWhitelist.join('|') + ')\\b', 'g'), "['$1']");
diff --git a/lodash.js b/lodash.js
index 104b2fa1a..9f05ed000 100644
--- a/lodash.js
+++ b/lodash.js
@@ -55,6 +55,9 @@
       reEmptyStringMiddle = /\b(__p \+=) '' \+/g,
       reEmptyStringTrailing = /(__e\(.*?\)|\b__t\)) \+\n'';/g;
 
+  /** Used to match regexp flags from their coerced string values */
+  var reFlags = /\w*$/;
+
   /** Used to insert the data object variable into compiled template source */
   var reInsertVariable = /(?:__e|__t = )\(\s*(?![\d\s"']|this\.)/g;
 
@@ -110,6 +113,7 @@
       dateClass = '[object Date]',
       funcClass = '[object Function]',
       numberClass = '[object Number]',
+      objectClass = '[object Object]',
       regexpClass = '[object RegExp]',
       stringClass = '[object String]';
 
@@ -159,6 +163,12 @@
   var arrayLikeClasses = {};
   arrayLikeClasses[argsClass] = arrayLikeClasses[arrayClass] = arrayLikeClasses[stringClass] = true;
 
+  /** Used to identify object classifications that `_.clone` supports */
+  var cloneableClasses = {};
+  cloneableClasses[arrayClass] = cloneableClasses[boolClass] = cloneableClasses[dateClass] =
+  cloneableClasses[numberClass] = cloneableClasses[objectClass] = cloneableClasses[regexpClass] =
+  cloneableClasses[stringClass] = true;
+
   /**
    * Used to escape characters for inclusion in HTML.
    * The `>` and `/` characters don't require escaping in HTML and have no
@@ -2464,23 +2474,129 @@
   /*--------------------------------------------------------------------------*/
 
   /**
-   * Create a shallow clone of the `value`. Any nested objects or arrays will be
-   * assigned by reference and not cloned.
+   * Create a clone of `value`. If `deep` is `true`, all nested objects, excluding
+   * functons and `arguments` objects, will be cloned otherwise they will be
+   * assigned by reference.
    *
    * @static
    * @memberOf _
    * @category Objects
    * @param {Mixed} value The value to clone.
+   * @param {Boolean} deep A flag to indicate a deep clone.
+   * @param {Object} [guard] Internally used to allow this method to work with
+   *  others like `_.map` without using their callback `index` argument for `deep`.
+   * @param {Array} [stack=[]] Internally used to keep track of traversed objects
+   *  to avoid circular references.
    * @returns {Mixed} Returns the cloned `value`.
    * @example
    *
+   * var stooges = [
+   *   { 'name': 'moe', 'age': 40 },
+   *   { 'name': 'larry', 'age': 50 },
+   *   { 'name': 'curly', 'age': 60 }
+   * ];
+   *
    * _.clone({ 'name': 'moe' });
-   * // => { 'name': 'moe' };
+   * // => { 'name': 'moe' }
+   *
+   * var shallow = _.clone(stooges);
+   * shallow[0] === stooges[0];
+   * // => true
+   *
+   * var deep = _.clone(stooges, true);
+   * shallow[0] === stooges[0];
+   * // => false
    */
-  function clone(value) {
-    return value && objectTypes[typeof value]
-      ? (isArray(value) ? value.slice() : extend({}, value))
-      : value;
+  function clone(value, deep, guard, stack) {
+    if (!value) {
+      return value;
+    }
+    var isObj = typeof value == 'object';
+    stack || (stack = []);
+
+    if (guard) {
+      deep = false;
+    }
+    // use custom `clone` method if available
+    if (value.clone && toString.call(value.clone) == funcClass) {
+      return value.clone(deep);
+    }
+    // inspect [[Class]]
+    if (isObj) {
+      var className = toString.call(value);
+
+      // don't clone `arguments` objects, functions, or non-object Objects
+      if (!cloneableClasses[className] || (noArgsClass && isArguments(value))) {
+        return value;
+      }
+
+      var ctor = value.constructor,
+          isArr = className == arrayClass,
+          useCtor = toString.call(ctor) == funcClass;
+
+      // IE < 9 presents nodes like `Object` objects:
+      // IE < 8 are missing the node's constructor property
+      // IE 8 node constructors are typeof "object"
+      // check if the constructor is `Object` as `Object instanceof Object` is `true`
+      if (className == objectClass &&
+          (isObj = useCtor && ctor instanceof ctor)) {
+        // An object's own properties are iterated before inherited properties.
+        // If the last iterated key belongs to an object's own property then
+        // there are no inherited enumerable properties.
+        forIn(value, function(objValue, objKey) { isObj = objKey; });
+        isObj = isObj == true || hasOwnProperty.call(value, isObj);
+      }
+    }
+    // shallow clone
+    if (!isObj || !deep) {
+      // don't clone functions
+      return isObj
+        ? (isArr ? slice.call(value) : extend({}, value))
+        : value;
+    }
+
+    switch (className) {
+      case boolClass:
+        return new ctor(value == true);
+
+      case dateClass:
+        return new ctor(+value);
+
+      case numberClass:
+      case stringClass:
+        return new ctor(value);
+
+      case regexpClass:
+        return ctor(value.source, reFlags.exec(value));
+    }
+
+    // check for circular references and return corresponding clone
+    var length = stack.length;
+    while (length--) {
+      if (stack[length].value == value) {
+        return stack[length].clone;
+      }
+    }
+
+    // init cloned object
+    length = value.length;
+    var result = isArr ? ctor(length) : (useCtor ? new ctor : {});
+
+    // add current clone and original value to the stack of traversed objects
+    stack.push({ 'clone': result, 'value': value });
+
+    // recursively populate clone (susceptible to call stack limits)
+    if (isArr) {
+      var index = -1;
+      while (++index < length) {
+        result[index] = clone(value[index], deep, null, stack);
+      }
+    } else {
+      forOwn(value, function(objValue, key) {
+        result[key] = clone(objValue, deep, null, stack);
+      });
+    }
+    return result;
   }
 
   /**
@@ -2780,8 +2896,8 @@
    * @category Objects
    * @param {Mixed} a The value to compare.
    * @param {Mixed} b The other value to compare.
-   * @param {Array} [stack] Internally used to keep track of "seen" objects to
-   *  avoid circular references.
+   * @param {Array} [stack=[]] Internally used to keep track of traversed objects
+   *  to avoid circular references.
    * @returns {Boolean} Returns `true` if the values are equvalent, else `false`.
    * @example
    *
diff --git a/test/test.js b/test/test.js
index 6a143ddd7..0d8d6b6d0 100644
--- a/test/test.js
+++ b/test/test.js
@@ -152,6 +152,102 @@
 
   /*--------------------------------------------------------------------------*/
 
+  QUnit.module('lodash.clone');
+
+  (function() {
+    function Klass() { }
+    Klass.prototype = { 'a': 1 };
+
+    var nonCloneable = {
+      'an arguments object': arguments,
+      'an element': window.document && document.body,
+      'a function': Klass,
+      'a Klass instance': new Klass
+    };
+
+    var objects = {
+      'an array': ['a', 'b', 'c', ''],
+      'an array-like-object': { '0': 'a', '1': 'b', '2': 'c',  '3': '', 'length': 5 },
+      'boolean': false,
+      'boolean object': Object(false),
+      'an object': { 'a': 0, 'b': 1, 'c': 3 },
+      'an object with object values': { 'a': /a/, 'b': ['B'], 'c': { 'C': 1 } },
+      'null': null,
+      'a number': 3,
+      'a number object': Object(3),
+      'a regexp': /a/gim,
+      'a string': 'a',
+      'a string object': Object('a'),
+      'undefined': undefined
+    };
+
+    objects['an array'].length = 5;
+
+    _.forOwn(objects, function(object, key) {
+      test('should deep clone ' + key + ' correctly', function() {
+        var clone = _.clone(object, true);
+
+        if (object == null) {
+          equal(clone, object);
+        } else {
+          deepEqual(clone.valueOf(), object.valueOf());
+        }
+        if (_.isObject(object)) {
+          ok(clone !== object);
+        } else {
+          skipTest();
+        }
+      });
+    });
+
+    _.forOwn(nonCloneable, function(object, key) {
+      test('should not clone ' + key, function() {
+        ok(_.clone(object) === object);
+        ok(_.clone(object, true) === object);
+      });
+    });
+
+    test('should shallow clone when used as `callback` for `_.map`', function() {
+      var expected = [{ 'a': [0] }, { 'b': [1] }],
+          actual = _.map(expected, _.clone);
+
+      ok(actual != expected && actual.a == expected.a && actual.b == expected.b);
+    });
+
+    test('should deep clone objects with circular references', function() {
+      var object = {
+        'foo': { 'b': { 'foo': { 'c': { } } } },
+        'bar': { }
+      };
+
+      object.foo.b.foo.c.foo = object;
+      object.bar.b = object.foo.b;
+
+      var clone = _.clone(object, true);
+      ok(clone.bar.b === clone.foo.b && clone === clone.foo.b.foo.c.foo && clone !== object);
+    });
+
+    test('should clone using Klass#clone', function() {
+      var object = new Klass;
+      Klass.prototype.clone = function() {  return new Klass; };
+
+      var clone = _.clone(object);
+      ok(clone !== object && clone instanceof Klass);
+
+      clone = _.clone(object, true);
+      ok(clone !== object && clone instanceof Klass);
+
+      delete Klass.prototype.clone;
+    });
+
+    test('should clone problem JScript properties (test in IE < 9)', function() {
+      deepEqual(_.clone(shadowed), shadowed);
+      deepEqual(_.clone(shadowed, true), shadowed);
+    });
+  }(1, 2, 3));
+
+  /*--------------------------------------------------------------------------*/
+
   QUnit.module('lodash.contains');
 
   (function() {