diff --git a/core/lib/Drupal/Core/Utility/ProjectInfo.php b/core/lib/Drupal/Core/Utility/ProjectInfo.php
index a2cf7a4..1ae1c4c 100644
--- a/core/lib/Drupal/Core/Utility/ProjectInfo.php
+++ b/core/lib/Drupal/Core/Utility/ProjectInfo.php
@@ -50,25 +50,8 @@ class ProjectInfo {
    */
   function processInfoList(array &$projects, array $list, $project_type, $status, array $additional_whitelist = array()) {
     foreach ($list as $file) {
-      // A disabled or hidden base theme of an enabled sub-theme still has all
-      // of its code run by the sub-theme, so we include it in our "enabled"
-      // projects list.
-      if ($status && !empty($file->sub_themes)) {
-        foreach ($file->sub_themes as $key => $name) {
-          // Build a list of installed sub-themes.
-          if ($list[$key]->status) {
-            $file->installed_sub_themes[$key] = $name;
-          }
-        }
-        // If the theme is uninstalled and there are no installed subthemes, we
-        // should ignore this base theme for the installed case. If the site is
-        // trying to display uninstalled themes, we'll catch it then.
-        if (!$file->status && empty($file->installed_sub_themes)) {
-          continue;
-        }
-      }
-      // Otherwise, just add projects of the proper status to our list.
-      elseif ($file->status != $status) {
+      // Just projects with a matching status should be listed.
+      if ($file->status != $status) {
         continue;
       }
 
@@ -77,9 +60,8 @@ function processInfoList(array &$projects, array $list, $project_type, $status,
         continue;
       }
 
-      // Skip if it's a hidden module or hidden theme without installed
-      // sub-themes.
-      if (!empty($file->info['hidden']) && empty($file->installed_sub_themes)) {
+      // Skip if it's a hidden project and the project is not installed.
+      if (!empty($file->info['hidden']) && empty($status)) {
         continue;
       }
 
@@ -120,25 +102,10 @@ function processInfoList(array &$projects, array $list, $project_type, $status,
       else {
         $project_display_type = $project_type;
       }
-      if (empty($status) && empty($file->installed_sub_themes)) {
+      if (empty($status)) {
         // If we're processing disabled modules or themes, append a suffix.
-        // However, we don't do this to a base theme with installed
-        // subthemes, since we treat that case as if it is installed.
         $project_display_type .= '-disabled';
       }
-      // Add a list of sub-themes that "depend on" the project and a list of base
-      // themes that are "required by" the project.
-      if ($project_name == 'drupal') {
-        // Drupal core is always required, so this extra info would be noise.
-        $sub_themes = array();
-        $base_themes = array();
-      }
-      else {
-        // Add list of installed sub-themes.
-        $sub_themes = !empty($file->installed_sub_themes) ? $file->installed_sub_themes : array();
-        // Add list of base themes.
-        $base_themes = !empty($file->base_themes) ? $file->base_themes : array();
-      }
       if (!isset($projects[$project_name])) {
         // Only process this if we haven't done this project, since a single
         // project can have multiple modules or themes.
@@ -151,8 +118,6 @@ function processInfoList(array &$projects, array $list, $project_type, $status,
           'includes' => array($file->getName() => $file->info['name']),
           'project_type' => $project_display_type,
           'project_status' => $status,
-          'sub_themes' => $sub_themes,
-          'base_themes' => $base_themes,
         );
       }
       elseif ($projects[$project_name]['project_type'] == $project_display_type) {
@@ -164,12 +129,6 @@ function processInfoList(array &$projects, array $list, $project_type, $status,
         $projects[$project_name]['includes'][$file->getName()] = $file->info['name'];
         $projects[$project_name]['info']['_info_file_ctime'] = max($projects[$project_name]['info']['_info_file_ctime'], $file->info['_info_file_ctime']);
         $projects[$project_name]['datestamp'] = max($projects[$project_name]['datestamp'], $file->info['datestamp']);
-        if (!empty($sub_themes)) {
-          $projects[$project_name]['sub_themes'] += $sub_themes;
-        }
-        if (!empty($base_themes)) {
-          $projects[$project_name]['base_themes'] += $base_themes;
-        }
       }
       elseif (empty($status)) {
         // If we have a project_name that matches, but the project_display_type
diff --git a/core/modules/update/src/UpdateManagerInterface.php b/core/modules/update/src/UpdateManagerInterface.php
index e1dd5a4..c011bae 100644
--- a/core/modules/update/src/UpdateManagerInterface.php
+++ b/core/modules/update/src/UpdateManagerInterface.php
@@ -51,10 +51,6 @@
    *     'theme'.
    *   - project_status: This indicates if the project is enabled and will
    *     always be TRUE, as the function only returns enabled projects.
-   *   - sub_themes: If the project is a theme it contains an associative array
-   *     of all sub-themes.
-   *   - base_themes: If the project is a theme it contains an associative array
-   *     of all base-themes.
    *
    * @see update_process_project_info()
    * @see update_calculate_project_data()
diff --git a/core/modules/update/templates/update-project-status.html.twig b/core/modules/update/templates/update-project-status.html.twig
index b00e0b2..4cc9a19 100644
--- a/core/modules/update/templates/update-project-status.html.twig
+++ b/core/modules/update/templates/update-project-status.html.twig
@@ -21,8 +21,6 @@
  *   - data: The data about an extra item.
  * - includes: The projects within the project.
  * - disabled: The currently disabled projects in the project.
- * - base_themes: The base themes supplied by the project.
- * - sub_themes: The subthemes supplied by the project.
  *
  * @see template_preprocess_update_project_status()
  *
@@ -105,18 +103,4 @@
       Includes: {{ includes|placeholder }}
     {% endtrans %}
   {% endif %}
-
-  {% if base_themes %}
-    {% set basethemes = base_themes|join(', ') %}
-    {% trans %}
-      Depends on: {{ basethemes }}
-    {% endtrans %}
-  {% endif %}
-
-  {% if sub_themes %}
-    {% set subthemes = sub_themes|join(', ') %}
-    {% trans %}
-      Required by: {{ subthemes|placeholder }}
-    {% endtrans %}
-  {% endif %}
 </div>
diff --git a/core/modules/update/update.report.inc b/core/modules/update/update.report.inc
index dd2494f..cb8c209 100644
--- a/core/modules/update/update.report.inc
+++ b/core/modules/update/update.report.inc
@@ -247,42 +247,6 @@ function template_preprocess_update_project_status(&$variables) {
     }
   }
 
-  if (!empty($project['base_themes'])) {
-    asort($project['base_themes']);
-    $base_themes = array();
-    foreach ($project['base_themes'] as $base_key => $base_theme) {
-      switch ($includes_status[$base_key]) {
-        case UPDATE_NOT_SECURE:
-          $base_status_label = t('Security update required!');
-          break;
-        case UPDATE_REVOKED:
-          $base_status_label = t('Revoked!');
-          break;
-        case UPDATE_NOT_SUPPORTED:
-          $base_status_label = t('Not supported!');
-          break;
-        default:
-          $base_status_label = '';
-      }
-
-      if ($base_status_label) {
-        $base_themes[] = t('%base_theme (!base_label)', array(
-          '%base_theme' => $base_theme,
-          '!base_label' => $base_status_label,
-        ));
-      }
-      else {
-        $base_themes[] = drupal_placeholder($base_theme);
-      }
-    }
-    $variables['base_themes'] = $base_themes;
-  }
-
-  if (!empty($project['sub_themes'])) {
-    sort($project['sub_themes']);
-    $variables['sub_themes'] = $project['sub_themes'];
-  }
-
   // Set the project status details.
   $status_label = NULL;
   switch ($project['status']) {