diff -u b/core/lib/Drupal/Core/Routing/UrlGenerator.php b/core/lib/Drupal/Core/Routing/UrlGenerator.php
--- b/core/lib/Drupal/Core/Routing/UrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/UrlGenerator.php
@@ -170,8 +170,6 @@
     $path = $this->getInternalPathFromRoute($route, $parameters);
     $path = $this->processPath($path, $options);
 
-    $absolute = !empty($options['absolute']);
-
     if (!empty($options['prefix'])) {
       $path = ltrim($path, '/');
       $prefix = empty($path) ? rtrim($options['prefix'], '/') : $options['prefix'];
@@ -185,8 +183,27 @@
       }
     }
 
-    $base_url = isset($options['base_url']) ? $options['base_url'] : $this->context->getBaseUrl();
-    if (!$absolute || preg_match('/^http(s)?\:\\/\//', $base_url) === 1 || !$host = $this->context->getHost()) {
+    // The base_url might be rewritten from the language rewrite in domain mode.
+    if (isset($options['base_url'])) {
+      $base_url = $options['base_url'];
+
+      if (isset($options['https']) && $this->mixedModeSessions) {
+        if ($options['https'] === TRUE) {
+          $base_url = str_replace('http://', 'https://', $base_url);
+        }
+        elseif ($options['https'] === FALSE) {
+          $base_url = str_replace('https://', 'http://', $base_url);
+        }
+      }
+
+      return $base_url . $path . $fragment;
+    }
+    else {
+      $base_url = $this->context->getBaseUrl();
+    }
+
+    $absolute = !empty($options['absolute']);
+    if (!$absolute || !$host = $this->context->getHost()) {
       return $base_url . $path . $fragment;
     }
 
diff -u b/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php b/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
--- b/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
@@ -266,6 +266,15 @@
     $url = $this->generator->generateFromRoute('test_1', array(), $options);
     $this->assertEquals('http://www.example.com:8888/hello/world', $url);
 
+    $options = array('base_url' => 'http://www.example.com:8888', 'https' => TRUE);
+    // Mixed-mode sessions are not enabled, so the https option is ignored.
+    $url = $this->generator->generateFromRoute('test_1', array(), $options);
+    $this->assertEquals('http://www.example.com:8888/hello/world', $url);
+
+    // Mixed-mode sessions are enabled, so the https option is obeyed.
+    $url = $this->generatorMixedMode->generateFromRoute('test_1', array(), $options);
+    $this->assertEquals('https://www.example.com:8888/hello/world', $url);
+
     $this->routeProcessorManager->expects($this->once())
       ->method('processOutbound')
       ->with($this->anything());