diff --git a/core/includes/common.inc b/core/includes/common.inc
index 0aeb3fa..585bd20 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -1090,7 +1090,7 @@ function valid_url($url, $absolute = FALSE) {
   if ($absolute) {
     return (bool)preg_match("
       /^                                                      # Start at the beginning of the text
-      (?:ftp|https?|feed):\/\/                                # Look for ftp, http, https or feed schemes
+      (?:ftp:|https?:|feed:)?\/\/                             # Look for ftp, http, https, feed or scheme relative schemes
       (?:                                                     # Userinfo (optional) which is typically
         (?:(?:[\w\.\-\+!$&'\(\)*\+,;=]|%[0-9a-f]{2})+:)*      # a username or a username and password
         (?:[\w\.\-\+%!$&'\(\)*\+,;=]|%[0-9a-f]{2})+@          # combination
diff --git a/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php b/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php
index b4cd7e7..d5b54e1 100644
--- a/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php
+++ b/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php
@@ -299,6 +299,20 @@ function testMenuQueryAndFragment() {
   }
 
   /**
+   * Add a menu link with a scheme-relative url.
+   */
+  function testMenuSchemeRelative() {
+    $this->drupalLogin($this->big_user);
+
+    // Make a path with query and fragment on.
+    $path = '//drupal.org';
+    $item = $this->addMenuLink(0, $path);
+
+    $this->drupalGet('admin/structure/menu/item/' . $item['mlid'] . '/edit');
+    $this->assertFieldByName('link_path', $path, 'Path is found with scheme-relative URL.');
+  }
+
+  /**
    * Add a menu link using the menu module UI.
    *
    * @param integer $plid Parent menu link id.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/UrlTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/UrlTest.php
index d178709..d60c2f1 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/UrlTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/UrlTest.php
@@ -217,4 +217,36 @@ function testExternalUrls() {
     $result = url($url, array('query' => $query));
     $this->assertEqual($url . '&' . http_build_query($query, '', '&'), $result, 'External URL query string can be extended with a custom query string in $options.');
   }
+
+  function testSchemeRelativeUrls() {
+    $test_url = '//drupal.org';
+
+    // Verify scheme-relative URL can contain a fragment.
+    $url = $test_url . '#drupal';
+    $result = url($url);
+    $this->assertEqual($url, $result, 'Scheme-relative URL with fragment works without a fragment in $options.');
+
+    // Verify fragment can be overidden in an external URL.
+    $url = $test_url . '#drupal';
+    $fragment = $this->randomName(10);
+    $result = url($url, array('fragment' => $fragment));
+    $this->assertEqual($test_url . '#' . $fragment, $result, 'Scheme-relative URL fragment is overidden with a custom fragment in $options.');
+
+    // Verify external URL can contain a query string.
+    $url = $test_url . '?drupal=awesome';
+    $result = url($url);
+    $this->assertEqual($url, $result, 'Scheme-relative URL with query string works without a query string in $options.');
+
+    // Verify external URL can be extended with a query string.
+    $url = $test_url;
+    $query = array($this->randomName(5) => $this->randomName(5));
+    $result = url($url, array('query' => $query));
+    $this->assertEqual($url . '?' . http_build_query($query, '', '&'), $result, 'Scheme-relative URL can be extended with a query string in $options.');
+
+    // Verify query string can be extended in an external URL.
+    $url = $test_url . '?drupal=awesome';
+    $query = array($this->randomName(5) => $this->randomName(5));
+    $result = url($url, array('query' => $query));
+    $this->assertEqual($url . '&' . http_build_query($query, '', '&'), $result, 'Scheme-relative URL query string can be extended with a custom query string in $options.');
+  }
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/ValidUrlUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/ValidUrlUnitTest.php
index bc9b6a9..32814f4 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/ValidUrlUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/ValidUrlUnitTest.php
@@ -25,7 +25,7 @@ public static function getInfo() {
    * Test valid absolute URLs.
    */
   function testValidAbsolute() {
-    $url_schemes = array('http', 'https', 'ftp');
+    $url_schemes = array('http://', 'https://', 'ftp://', '//');
     $valid_absolute_urls = array(
       'example.com',
       'www.example.com',
@@ -49,7 +49,7 @@ function testValidAbsolute() {
 
     foreach ($url_schemes as $scheme) {
       foreach ($valid_absolute_urls as $url) {
-        $test_url = $scheme . '://' . $url;
+        $test_url = $scheme . $url;
         $valid_url = valid_url($test_url, TRUE);
         $this->assertTrue($valid_url, format_string('@url is a valid URL.', array('@url' => $test_url)));
       }
@@ -60,7 +60,7 @@ function testValidAbsolute() {
    * Test invalid absolute URLs.
    */
   function testInvalidAbsolute() {
-    $url_schemes = array('http', 'https', 'ftp');
+    $url_schemes = array('http://', 'https://', 'ftp://', '//');
     $invalid_ablosule_urls = array(
       '',
       'ex!ample.com',
@@ -69,7 +69,7 @@ function testInvalidAbsolute() {
 
     foreach ($url_schemes as $scheme) {
       foreach ($invalid_ablosule_urls as $url) {
-        $test_url = $scheme . '://' . $url;
+        $test_url = $scheme . $url;
         $valid_url = valid_url($test_url, TRUE);
         $this->assertFalse($valid_url, format_string('@url is NOT a valid URL.', array('@url' => $test_url)));
       }