diff -u b/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php b/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php
--- b/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php
+++ b/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php
@@ -58,16 +58,9 @@
    *     \Drupal::languageManager()->getCurrentLanguage(LanguageInterface::TYPE_URL).
    *   - 'https': Whether this URL should point to a secure location. If not
    *     defined, the current scheme is used, so the user stays on HTTP or HTTPS
-<<<<<<< HEAD
    *     respectively. TRUE enforces HTTPS and FALSE enforces HTTP.
-   *   - 'base_url': Only used internally, to modify the base URL when a language
-   *     dependent URL requires so.
-=======
-   *     respectively. TRUE enforces HTTPS and FALSE enforces HTTP, but HTTPS can
-   *     only be enforced when the variable 'https' is set to TRUE.
    *   - 'base_url': Only used internally by a path processor, for example, to
    *     modify the base URL when a language dependent URL requires so.
->>>>>>> Docblock update.
    *   - 'prefix': Only used internally, to modify the path when a language
    *     dependent URL requires so.
    *   - 'script': Added to the URL between the base path and the path prefix.
only in patch2:
unchanged:
--- a/core/modules/language/src/Tests/LanguageSwitchingTest.php
+++ b/core/modules/language/src/Tests/LanguageSwitchingTest.php
@@ -7,7 +7,10 @@
 
 namespace Drupal\language\Tests;
 
+use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationUrl;
 use Drupal\Core\Language\LanguageInterface;
+use Drupal\Core\Routing\UrlGenerator;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -159,6 +162,72 @@ protected function doTestLanguageBlockAnonymous($block_label) {
   }
 
   /**
+   * Test languge switcher links for domain based negotiation
+   */
+
+  function testLanguageBlockWithDomain() {
+    global $base_url;
+
+    // Get the current host URI we're running on.
+    $base_url_host = parse_url($base_url, PHP_URL_HOST);
+
+    // Add the Italian language.
+    ConfigurableLanguage::createFromLangcode('it')->save();
+
+    $languages = $this->container->get('language_manager')->getLanguages();
+
+    // Enable browser and URL language detection.
+    $edit = array(
+      'language_interface[enabled][language-url]' => TRUE,
+      'language_interface[weight][language-url]' => -10,
+    );
+    $this->drupalPostForm('admin/config/regional/language/detection', $edit, t('Save settings'));
+
+    // Do not allow blank domain.
+    $edit = array(
+      'language_negotiation_url_part' => LanguageNegotiationUrl::CONFIG_DOMAIN,
+      'domain[en]' => '',
+    );
+    $this->drupalPostForm('admin/config/regional/language/detection/url', $edit, t('Save configuration'));
+    $this->assertText('The domain may not be left blank for English', 'The form does not allow blank domains.');
+    $this->rebuildContainer();
+
+    // Change the domain for the Italian language.
+    $edit = array(
+      'language_negotiation_url_part' => LanguageNegotiationUrl::CONFIG_DOMAIN,
+      'domain[en]' => $base_url_host,
+      'domain[it]' => 'it.example.com',
+    );
+    $this->drupalPostForm('admin/config/regional/language/detection/url', $edit, t('Save configuration'));
+    $this->assertText('The configuration options have been saved', 'Domain configuration is saved.');
+    $this->rebuildContainer();
+
+    // Enable the language switcher block.
+    $this->drupalPlaceBlock('language_block:' . LanguageInterface::TYPE_INTERFACE, array('id' => 'test_language_block'));
+
+    $this->drupalGet('');
+
+    /** @var UrlGenerator $generator */
+    $generator = $this->container->get('url_generator');
+
+    // Verfify the English URL is correct
+    list($english_link) = $this->xpath('//div[@id=:id]/ul/li/a[@hreflang=:hreflang]', array(
+      ':id' => 'block-test-language-block',
+      ':hreflang' => 'en',
+    ));
+    $english_url = $generator->generateFromPath('user/2', array('language' => $languages['en']));
+    $this->assertEqual($english_url, (string) $english_link['href']);
+
+    // Verfify the Italian URL is correct
+    list($italian_link) = $this->xpath('//div[@id=:id]/ul/li/a[@hreflang=:hreflang]', array(
+      ':id' => 'block-test-language-block',
+      ':hreflang' => 'it',
+    ));
+    $italian_url = $generator->generateFromPath('user/2', array('language' => $languages['it']));
+    $this->assertEqual($italian_url, (string) $italian_link['href']);
+  }
+
+  /**
    * Test active class on links when switching languages.
    */
   function testLanguageLinkActiveClass() {