diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 2aef832c..a9e9441 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -330,10 +330,10 @@ function theme_get_setting($setting_name, $theme = NULL) {
       if ($cache[$theme]->get('features.logo')) {
         $logo_path = $cache[$theme]->get('logo.path');
         if ($cache[$theme]->get('logo.use_default')) {
-          $cache[$theme]->set('logo.url', file_create_url($theme_object->getPath() . '/logo.svg'));
+          $cache[$theme]->set('logo.url', file_url_transform_relative(file_create_url($theme_object->getPath() . '/logo.svg')));
         }
         elseif ($logo_path) {
-          $cache[$theme]->set('logo.url', file_create_url($logo_path));
+          $cache[$theme]->set('logo.url', file_url_transform_relative(file_create_url($logo_path)));
         }
       }
 
@@ -342,14 +342,14 @@ function theme_get_setting($setting_name, $theme = NULL) {
         $favicon_path = $cache[$theme]->get('favicon.path');
         if ($cache[$theme]->get('favicon.use_default')) {
           if (file_exists($favicon = $theme_object->getPath() . '/favicon.ico')) {
-            $cache[$theme]->set('favicon.url', file_create_url($favicon));
+            $cache[$theme]->set('favicon.url', file_url_transform_relative(file_create_url($favicon)));
           }
           else {
-            $cache[$theme]->set('favicon.url', file_create_url('core/misc/favicon.ico'));
+            $cache[$theme]->set('favicon.url', file_url_transform_relative(file_create_url('core/misc/favicon.ico')));
           }
         }
         elseif ($favicon_path) {
-          $cache[$theme]->set('favicon.url', file_create_url($favicon_path));
+          $cache[$theme]->set('favicon.url', file_url_transform_relative(file_create_url($favicon_path)));
         }
         else {
           $cache[$theme]->set('features.favicon', FALSE);
diff --git a/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php b/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php
index eeed904..3b192b4 100644
--- a/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php
+++ b/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php
@@ -134,7 +134,7 @@ public function render(array $css_assets) {
           // assets: output a LINK tag for a file CSS asset.
           if (count($css_assets) <= 31) {
             $element = $link_element_defaults;
-            $element['#attributes']['href'] = file_create_url($css_asset['data']) . $query_string_separator . $query_string;
+            $element['#attributes']['href'] = file_url_transform_relative(file_create_url($css_asset['data'])) . $query_string_separator . $query_string;
             $element['#attributes']['media'] = $css_asset['media'];
             $element['#browsers'] = $css_asset['browsers'];
             $elements[] = $element;
@@ -167,7 +167,7 @@ public function render(array $css_assets) {
                 // control browser-caching. IE7 does not support a media type on
                 // the @import statement, so we instead specify the media for
                 // the group on the STYLE tag.
-                $import[] = '@import url("' . SafeMarkup::checkPlain(file_create_url($next_css_asset['data']) . '?' . $query_string) . '");';
+                $import[] = '@import url("' . SafeMarkup::checkPlain(file_url_transform_relative(file_create_url($next_css_asset['data'])) . '?' . $query_string) . '");';
                 // Move the outer for loop skip the next item, since we
                 // processed it here.
                 $i = $j;
diff --git a/core/lib/Drupal/Core/Asset/JsCollectionRenderer.php b/core/lib/Drupal/Core/Asset/JsCollectionRenderer.php
index 7db84ab..e40d0f0 100644
--- a/core/lib/Drupal/Core/Asset/JsCollectionRenderer.php
+++ b/core/lib/Drupal/Core/Asset/JsCollectionRenderer.php
@@ -80,7 +80,7 @@ public function render(array $js_assets) {
         case 'file':
           $query_string = $js_asset['version'] == -1 ? $default_query_string : 'v=' . $js_asset['version'];
           $query_string_separator = (strpos($js_asset['data'], '?') !== FALSE) ? '&' : '?';
-          $element['#attributes']['src'] = file_create_url($js_asset['data']);
+          $element['#attributes']['src'] = file_url_transform_relative(file_create_url($js_asset['data']));
           // Only add the cache-busting query string if this isn't an aggregate
           // file.
           if (!isset($js_asset['preprocessed'])) {