diff --git a/core/includes/file.inc b/core/includes/file.inc
index f141cc8..86ce929 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -5,6 +5,7 @@
  * API for handling file uploads and server file management.
  */
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\StreamWrapper\LocalStream;
 use Drupal\Component\PhpStorage\FileStorage;
 use Drupal\Component\Utility\Settings;
@@ -469,7 +470,7 @@ function file_create_url($uri) {
     else {
       // If this is not a properly formatted stream, then it is a shipped file.
       // Therefore, return the urlencoded URI with the base URL prepended.
-      return $GLOBALS['base_url'] . '/' . drupal_encode_path($uri);
+      return $GLOBALS['base_url'] . '/' . UrlHelper::encodePath($uri);
     }
   }
   elseif ($scheme == 'http' || $scheme == 'https') {
diff --git a/core/includes/form.inc b/core/includes/form.inc
index 5b292f5..a1a44d7 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -2623,7 +2623,7 @@ function form_validate_url(&$element, &$form_state) {
   $value = trim($element['#value']);
   form_set_value($element, $value, $form_state);
 
-  if ($value !== '' && !valid_url($value, TRUE)) {
+  if ($value !== '' && !UrlHelper::isValid($value, TRUE)) {
     form_error($element, $form_state, t('The URL %url is not valid.', array('%url' => $value)));
   }
 }
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 616637c..7309ca6 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -1,5 +1,6 @@
 <?php
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Component\Utility\UserAgent;
 use Drupal\Component\Utility\Crypt;
 
@@ -846,7 +847,7 @@ function install_get_form($form_id, array &$install_state) {
  * @see install_full_redirect_url()
  */
 function install_redirect_url($install_state) {
-  return 'core/install.php?' . drupal_http_build_query($install_state['parameters']);
+  return 'core/install.php?' . UrlHelper::buildQuery($install_state['parameters']);
 }
 
 /**
diff --git a/core/includes/install.inc b/core/includes/install.inc
index 8ba52b6..f1491c5 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -9,6 +9,7 @@
 use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\OpCodeCache;
 use Drupal\Component\Utility\Settings;
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Database\Database;
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\Extension\ExtensionDiscovery;
@@ -933,7 +934,7 @@ function drupal_current_script_url($query = array()) {
   $uri = $_SERVER['SCRIPT_NAME'];
   $query = array_merge(drupal_get_query_parameters(), $query);
   if (!empty($query)) {
-    $uri .= '?' . drupal_http_build_query($query);
+    $uri .= '?' . UrlHelper::buildQuery($query);
   }
   return $uri;
 }
diff --git a/core/lib/Drupal/Core/EventSubscriber/RedirectResponseSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/RedirectResponseSubscriber.php
index 6cc7916..c7687fa 100644
--- a/core/lib/Drupal/Core/EventSubscriber/RedirectResponseSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/RedirectResponseSubscriber.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\EventSubscriber;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Routing\UrlGeneratorInterface;
 use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
@@ -54,8 +55,8 @@ public function checkRedirectUrl(FilterResponseEvent $event) {
       // the following exception:
       // - Absolute URLs that point to this site (i.e. same base URL and
       //   base path) are allowed.
-      if ($destination && (!url_is_external($destination) || _external_url_is_local($destination))) {
-        $destination = drupal_parse_url($destination);
+      if ($destination && (!UrlHelper::isExternal($destination) || UrlHelper::externalIsLocal($destination, base_path()))) {
+        $destination = UrlHelper::parse($destination);
 
         $path = $destination['path'];
         $options['query'] = $destination['query'];
diff --git a/core/lib/Drupal/Core/Routing/UrlGenerator.php b/core/lib/Drupal/Core/Routing/UrlGenerator.php
index 2402708..7197473 100644
--- a/core/lib/Drupal/Core/Routing/UrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/UrlGenerator.php
@@ -246,8 +246,9 @@ public function generateFromPath($path = NULL, $options = array()) {
       // call the slow
       // \Drupal\Component\Utility\UrlHelper::stripDangerousProtocols() if $path
       // contains a ':' before any / ? or #. Note: we could use
-      // url_is_external($path) here, but that would require another function
-      // call, and performance inside url() is critical.
+      // Drupal\Component\Utility\UrlHelper::isExternal($path) here, but that
+      // would require another function call, and performance inside url() is
+      // critical.
       $colonpos = strpos($path, ':');
       $options['external'] = ($colonpos !== FALSE && !preg_match('![/?#]!', substr($path, 0, $colonpos)) && UrlHelper::stripDangerousProtocols($path) == $path);
     }
diff --git a/core/lib/Drupal/Core/StreamWrapper/PublicStream.php b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
index 8f798f5..3563cf1 100644
--- a/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\StreamWrapper;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Component\Utility\Settings;
 
 /**
@@ -29,7 +30,7 @@ public function getDirectoryPath() {
    */
   public function getExternalUrl() {
     $path = str_replace('\\', '/', $this->getTarget());
-    return $GLOBALS['base_url'] . '/' . self::getDirectoryPath() . '/' . drupal_encode_path($path);
+    return $GLOBALS['base_url'] . '/' . self::getDirectoryPath() . '/' . UrlHelper::encodePath($path);
   }
 
   /**
diff --git a/core/modules/contextual/lib/Drupal/contextual/Plugin/views/field/ContextualLinks.php b/core/modules/contextual/lib/Drupal/contextual/Plugin/views/field/ContextualLinks.php
index 21ff324..f2d45a2 100644
--- a/core/modules/contextual/lib/Drupal/contextual/Plugin/views/field/ContextualLinks.php
+++ b/core/modules/contextual/lib/Drupal/contextual/Plugin/views/field/ContextualLinks.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\contextual\Plugin\views\field;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\views\Plugin\views\field\FieldPluginBase;
 use Drupal\views\ResultRow;
 use Drupal\Component\Utility\Json;
@@ -115,7 +116,7 @@ public function render(ResultRow $values) {
           '',
           array(),
           array(
-            'contextual-views-field-links' => drupal_encode_path(Json::encode($links)),
+            'contextual-views-field-links' => UrlHelper::encodePath(Json::encode($links)),
           )
         )
       );
diff --git a/core/modules/locale/locale.module b/core/modules/locale/locale.module
index e6d9a6f..1be2852 100644
--- a/core/modules/locale/locale.module
+++ b/core/modules/locale/locale.module
@@ -10,6 +10,7 @@
  * object files are supported.
  */
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Component\Utility\Json;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Language\Language;
@@ -1117,7 +1118,7 @@ function _locale_strip_quotes($string) {
 function _locale_parse_js_file($filepath) {
   // The file path might contain a query string, so make sure we only use the
   // actual file.
-  $parsed_url = drupal_parse_url($filepath);
+  $parsed_url = UrlHelper::parse($filepath);
   $filepath = $parsed_url['path'];
 
   // If there is still a protocol component in the path, reject that.
diff --git a/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php b/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php
index ebb28bf..38024a8 100644
--- a/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/Entity/MenuLink.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\menu_link\Entity;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\Entity;
 use Drupal\Core\Entity\EntityStorageInterface;
@@ -476,7 +477,7 @@ public function preSave(EntityStorageInterface $storage) {
 
     // This is the easiest way to handle the unique internal path '<front>',
     // since a path marked as external does not need to match a route.
-    $this->external = (url_is_external($this->link_path) || $this->link_path == '<front>') ? 1 : 0;
+    $this->external = (UrlHelper::isExternal($this->link_path) || $this->link_path == '<front>') ? 1 : 0;
 
     // Try to find a parent link. If found, assign it and derive its menu.
     $parent = $this->findParent($storage);
diff --git a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
index 3f4617e..a2fee26 100644
--- a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\menu_link;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Entity\EntityFormController;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Path\AliasManagerInterface;
@@ -212,7 +213,7 @@ public function validate(array $form, array &$form_state) {
       $menu_link->link_path = $normal_path;
       $form_state['values']['link_path'] = $normal_path;
     }
-    if (!url_is_external($menu_link->link_path)) {
+    if (!UrlHelper::isExternal($menu_link->link_path)) {
       $parsed_link = parse_url($menu_link->link_path);
       if (isset($parsed_link['query'])) {
         $menu_link->options['query'] = array();
diff --git a/core/modules/shortcut/shortcut.module b/core/modules/shortcut/shortcut.module
index 5f84440..130b294 100644
--- a/core/modules/shortcut/shortcut.module
+++ b/core/modules/shortcut/shortcut.module
@@ -5,6 +5,7 @@
  * Allows users to manage customizable lists of shortcut links.
  */
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Routing\UrlMatcher;
 use Drupal\Core\Url;
 use Drupal\shortcut\ShortcutSetInterface;
@@ -278,7 +279,7 @@ function shortcut_valid_link($path) {
   }
 
   // An empty path is valid too and will be converted to <front>.
-  return (!url_is_external($path) && (\Drupal::service('router.route_provider')->getRoutesByPattern('/' . $path)->count() > 0)) || empty($path) || $path == '<front>';
+  return (!UrlHelper::isExternal($path) && (\Drupal::service('router.route_provider')->getRoutesByPattern('/' . $path)->count() > 0)) || empty($path) || $path == '<front>';
 }
 
 /**
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 3487fd4..af0d580 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/UrlTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/UrlTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Common;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Language\Language;
 use Drupal\simpletest\WebTestBase;
 use Symfony\Component\HttpFoundation\Request;
@@ -25,7 +26,7 @@ class UrlTest extends WebTestBase {
   public static function getInfo() {
     return array(
       'name' => 'URL generation tests',
-      'description' => 'Confirm that url(), drupal_get_query_parameters(), drupal_http_build_query(), and l() work correctly with various input.',
+      'description' => 'Confirm that url(), drupal_get_query_parameters(), Drupal\Component\Utility\UrlHelper::buildQuery(), and l() work correctly with various input.',
       'group' => 'Common',
     );
   }
@@ -219,7 +220,7 @@ function testDrupalGetQueryParameters() {
   }
 
   /**
-   * Tests drupal_parse_url().
+   * Tests UrlHelper::parse().
    */
   function testDrupalParseUrl() {
     // Relative, absolute, and external URLs, without/with explicit script path,
@@ -233,7 +234,7 @@ function testDrupalParseUrl() {
             'query' => array('foo' => 'bar', 'bar' => 'baz', 'baz' => ''),
             'fragment' => 'foo',
           );
-          $this->assertEqual(drupal_parse_url($url), $expected, 'URL parsed correctly.');
+          $this->assertEqual(UrlHelper::parse($url), $expected, 'URL parsed correctly.');
         }
       }
     }
@@ -245,15 +246,15 @@ function testDrupalParseUrl() {
       'query' => array(),
       'fragment' => '',
     );
-    $this->assertEqual(drupal_parse_url($url), $result, 'Relative URL parsed correctly.');
+    $this->assertEqual(UrlHelper::parse($url), $result, 'Relative URL parsed correctly.');
 
     // Test that drupal can recognize an absolute URL. Used to prevent attack vectors.
     $url = 'http://drupal.org/foo/bar?foo=bar&bar=baz&baz#foo';
-    $this->assertTrue(url_is_external($url), 'Correctly identified an external URL.');
+    $this->assertTrue(UrlHelper::isExternal($url), 'Correctly identified an external URL.');
 
-    // Test that drupal_parse_url() does not allow spoofing a URL to force a malicious redirect.
-    $parts = drupal_parse_url('forged:http://cwe.mitre.org/data/definitions/601.html');
-    $this->assertFalse(valid_url($parts['path'], TRUE), 'drupal_parse_url() correctly parsed a forged URL.');
+    // Test that UrlHelper::parse() does not allow spoofing a URL to force a malicious redirect.
+    $parts = UrlHelper::parse('forged:http://cwe.mitre.org/data/definitions/601.html');
+    $this->assertFalse(UrlHelper::isValid($parts['path'], TRUE), '\Drupal\Component\Utility\UrlHelper::isValid() correctly parsed a forged URL.');
   }
 
   /**
diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php b/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php
index 08c12cc..1517131 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php
@@ -9,6 +9,7 @@
 
 use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\views\Plugin\views\HandlerBase;
 use Drupal\views\Plugin\views\display\DisplayPluginBase;
 use Drupal\views\ResultRow;
@@ -1423,7 +1424,7 @@ protected function renderAsLink($alter, $text, $tokens) {
     if (isset($alter['query'])) {
       // Convert the query to a string, perform token replacement, and then
       // convert back to an array form for l().
-      $options['query'] = drupal_http_build_query($alter['query']);
+      $options['query'] = UrlHelper::buildQuery($alter['query']);
       $options['query'] = strtr($options['query'], $tokens);
       $query = array();
       parse_str($options['query'], $query);
diff --git a/core/modules/views/lib/Drupal/views/Tests/Handler/FieldWebTest.php b/core/modules/views/lib/Drupal/views/Tests/Handler/FieldWebTest.php
index dc9e3e8..d4b1781 100644
--- a/core/modules/views/lib/Drupal/views/Tests/Handler/FieldWebTest.php
+++ b/core/modules/views/lib/Drupal/views/Tests/Handler/FieldWebTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\views\Tests\Handler;
 
+use Drupal\Component\Utility\UrlHelper;
 use Drupal\views\Views;
 
 /**
@@ -284,11 +285,11 @@ public function testAlterUrl() {
     $id_field->options['alter']['path_case'] = 'ucfirst';
     $id_field->options['alter']['path'] = 'drupal has a great community';
     $output = $id_field->theme($row);
-    $this->assertSubString($output, drupal_encode_path('Drupal has a great community'));
+    $this->assertSubString($output, UrlHelper::encodePath('Drupal has a great community'));
 
     $id_field->options['alter']['path_case'] = 'ucwords';
     $output = $id_field->theme($row);
-    $this->assertSubString($output, drupal_encode_path('Drupal Has A Great Community'));
+    $this->assertSubString($output, UrlHelper::encodePath('Drupal Has A Great Community'));
     unset($id_field->options['alter']['path_case']);
 
     // Tests the linkclass setting and see whether it actuall exists in the output.