diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index d42c550..acf0ddb 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -721,6 +721,13 @@ protected function moduleData($module) {
       $profile_directories = array_map(function ($profile) {
         return $profile->getPath();
       }, $profiles);
+
+      // Allow additional profile directories to be added from settings.php.
+      // This provides support for "base profiles".
+      $settings_profile_directories = Settings::get('profile_directories');
+      if (!empty($settings_profile_directories)) {
+        $profile_directories = array_merge($settings_profile_directories, $profile_directories);
+      }
       $listing->setProfileDirectories($profile_directories);
 
       // Now find modules.
diff --git a/core/lib/Drupal/Core/Extension/ExtensionDiscovery.php b/core/lib/Drupal/Core/Extension/ExtensionDiscovery.php
index 3d68561..fb8c3dd 100644
--- a/core/lib/Drupal/Core/Extension/ExtensionDiscovery.php
+++ b/core/lib/Drupal/Core/Extension/ExtensionDiscovery.php
@@ -22,6 +22,13 @@
  * @encode
  * to your settings.php.
  *
+ * To add additional profile directories, add
+ * @code
+ * $settings['profile_directories'] = array(path);
+ * @encode
+ * to your settings.php.  If multiple paths are specified, they are searched
+ * from last to first.
+ *
  */
 class ExtensionDiscovery {
 
@@ -256,6 +263,14 @@ public function setProfileDirectoriesFromSettings() {
     if ($profile) {
       $this->profileDirectories[] = drupal_get_path('profile', $profile);
     }
+
+    // Allow additional profile directories to be added from settings.php.
+    // This provides support for "base profiles".
+    $settings_profile_directories = Settings::get('profile_directories');
+    if (!empty($settings_profile_directories)) {
+      $this->profileDirectories = array_merge($settings_profile_directories, $this->profileDirectories);
+    }
+
     return $this;
   }