diff --git a/includes/common.inc b/includes/common.inc
index 262e1c57b8591694acd0f2d97a5728a65e98b630..98713800dc88ea0c91f6dc53f492f645a2d3d74c 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -4098,7 +4098,12 @@ function drupal_region_class($region) {
  *       happened later in the page request gets added to the page after one for
  *       which drupal_add_js() happened earlier in the page request.
  *   - defer: If set to TRUE, the defer attribute is set on the <script>
- *     tag. Defaults to FALSE.
+ *     tag. Defaults to FALSE. Note that setting this to TRUE will disable
+ *     preprocessing as though the 'preprocess' option was set to FALSE.
+ *   - attributes: An associative array of attributes for the <script> tag.
+ *     This may be used to add 'defer', 'async' or custom attributes. Note that
+ *     setting any attributes will disable preprocessing as though the
+ *     'preprocess' option was set to FALSE.
  *   - cache: If set to FALSE, the JavaScript file is loaded anew on every page
  *     call; in other words, it is not cached. Used only when 'type' references
  *     a JavaScript file. Defaults to TRUE.
@@ -4163,6 +4168,7 @@ function drupal_add_js($data = NULL, $options = NULL) {
           'preprocess' => TRUE,
           'cache' => TRUE,
           'defer' => FALSE,
+          'attributes' => array(),
         ),
       );
       // Register all required libraries.
@@ -4211,6 +4217,7 @@ function drupal_js_defaults($data = NULL) {
     'preprocess' => TRUE,
     'version' => NULL,
     'data' => $data,
+    'attributes' => array(),
   );
 }
 
@@ -4336,7 +4343,10 @@ function drupal_get_js($scope = 'header', $javascript = NULL, $skip_alter = FALS
       case 'inline':
         $js_element = $element;
         if ($item['defer']) {
-          $js_element['#attributes']['defer'] = 'defer';
+          $item['attributes']['defer'] = 'defer';
+        }
+        if ($item['attributes']) {
+          $js_element['#attributes'] += $item['attributes'];
         }
         $js_element['#value_prefix'] = $embed_prefix;
         $js_element['#value'] = $item['data'];
@@ -4346,9 +4356,12 @@ function drupal_get_js($scope = 'header', $javascript = NULL, $skip_alter = FALS
 
       case 'file':
         $js_element = $element;
-        if (!$item['preprocess'] || !$preprocess_js) {
+        if (!$item['preprocess'] || !$preprocess_js || $item['defer'] || $item['attributes']) {
           if ($item['defer']) {
-            $js_element['#attributes']['defer'] = 'defer';
+            $item['attributes']['defer'] = 'defer';
+          }
+          if ($item['attributes']) {
+            $js_element['#attributes'] += $item['attributes'];
           }
           $query_string_separator = (strpos($item['data'], '?') !== FALSE) ? '&' : '?';
           $js_element['#attributes']['src'] = file_create_url($item['data']) . $query_string_separator . ($item['cache'] ? $query_string : REQUEST_TIME);
@@ -4372,7 +4385,10 @@ function drupal_get_js($scope = 'header', $javascript = NULL, $skip_alter = FALS
         $js_element = $element;
         // Preprocessing for external JavaScript files is ignored.
         if ($item['defer']) {
-          $js_element['#attributes']['defer'] = 'defer';
+          $item['attributes']['defer'] = 'defer';
+        }
+        if ($item['attributes']) {
+          $js_element['#attributes'] += $item['attributes'];
         }
         $js_element['#attributes']['src'] = $item['data'];
         $processed[$index++] = theme('html_tag', array('element' => $js_element));
diff --git a/modules/simpletest/tests/common.test b/modules/simpletest/tests/common.test
index 8694ff32e6703df80791f18981a87684504aab82..c3e5afd7a8d4aaa8542f17d067c5bb98f0853d8f 100644
--- a/modules/simpletest/tests/common.test
+++ b/modules/simpletest/tests/common.test
@@ -1439,6 +1439,43 @@ class JavaScriptTestCase extends DrupalWebTestCase {
   }
 
   /**
+   * Tests adding JavaScript files with additional attributes.
+   */
+  function testAttributes() {
+    $default_query_string = variable_get('css_js_query_string', '0');
+
+    drupal_add_js('http://example.com/script.js', array('attributes' => array('defer' => 'defer')));
+    drupal_add_js('misc/collapse.js', array('attributes' => array('defer' => 'defer')));
+    $javascript = drupal_get_js();
+
+    $expected_1 = '<script type="text/javascript" defer="defer" src="http://example.com/script.js?' . $default_query_string . '"></script>';
+    $expected_2 = '<script type="text/javascript" defer="defer" src="' . file_create_url('misc/collapse.js') . '?' . $default_query_string . '"></script>';
+
+    $this->assertTrue(strpos($javascript, $expected_1) > 0, 'Rendered external JavaScript with correct defer attribute.');
+    $this->assertTrue(strpos($javascript, $expected_2) > 0, 'Rendered internal JavaScript with correct defer attribute.');
+  }
+
+  /**
+   * Tests that attributes are maintained when JS aggregation is enabled.
+   */
+  function testAggregatedAttributes() {
+    // Enable aggregation.
+    variable_set('preprocess_js', TRUE);
+
+    $default_query_string = variable_get('css_js_query_string', '0');
+
+    drupal_add_js('http://example.com/script.js', array('attributes' => array('defer' => 'defer')));
+    drupal_add_js('misc/collapse.js', array('attributes' => array('defer' => 'defer')));
+    $javascript = drupal_get_js();
+
+    $expected_1 = '<script type="text/javascript" defer="defer" src="http://example.com/script.js?' . $default_query_string . '"></script>';
+    $expected_2 = '<script type="text/javascript" defer="defer" src="' . file_create_url('misc/collapse.js') . '?' . $default_query_string . '"></script>';
+
+    $this->assertTrue(strpos($javascript, $expected_1) > 0, 'Rendered external JavaScript with correct defer attribute with aggregation enabled.');
+    $this->assertTrue(strpos($javascript, $expected_2) > 0, 'Rendered internal JavaScript with correct defer attribute with aggregation enabled.');
+  }
+
+  /**
    * Test altering a JavaScript's weight via hook_js_alter().
    *
    * @see simpletest_js_alter()