diff --git a/README.txt b/README.txt
index 4d7b148..b5d7567 100644
--- a/README.txt
+++ b/README.txt
@@ -267,6 +267,8 @@ You can put your Drush command file in a number of places:
 
   d) In the system-wide Drush commands folder, e.g. /usr/share/drush/commands
 
+  e) In Drupal's sites/all/drush folder.
+
 In any case, it is important that you end the filename with ".drush.inc", so
 that Drush can find it.
 
diff --git a/includes/command.inc b/includes/command.inc
index 194068e..e86c05a 100644
--- a/includes/command.inc
+++ b/includes/command.inc
@@ -1169,6 +1169,8 @@ function _drush_find_commandfiles($phase, $phase_max = FALSE) {
       if (drush_drupal_major_version() >=8) {
         $searchpath[] = 'modules';
       }
+      // Include command files in sites/all/drush and the themes directories.
+      $searchpath[] = 'sites/all/drush';
       $searchpath[] = 'sites/all/themes';
       $searchpath[] = conf_path() . '/themes';
       break;