diff --git a/core/includes/common.inc b/core/includes/common.inc
index f8a54e9..5f52de1 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -2007,7 +2007,21 @@ function format_date($timestamp, $type = 'medium', $format = '', $timezone = NUL
 
   // Call date_format().
   $settings = array('langcode' => $langcode);
-  return $date_time->format($format, $settings);
+  $formatted_date = $date_time->format($format, $settings);
+  
+  $context = array(
+    'settings' => $settings,
+    'date_time' => $date_time,
+    'timezones' => $timezones,
+    'timestamp' => $timestamp,
+    'type' => $type,
+    'format' => $format,
+    'timezone' => $timezone,
+    'langcode' => $langcode,
+  );
+  drupal_alter('format_date', $formatted_date, $context);
+  
+  return $formatted_date;
 }
 
 /**
diff --git a/core/modules/system/system.api.php b/core/modules/system/system.api.php
index e9c0860..0568138 100644
--- a/core/modules/system/system.api.php
+++ b/core/modules/system/system.api.php
@@ -3946,6 +3946,29 @@ function hook_filetransfer_info_alter(&$filetransfer_info) {
 }
 
 /**
+ * Alter the formatted date.
+ *
+ * A module may implement this hook in order to alter the formatted date string
+ *
+ * @param $formatted_date
+ *   Formatted date in string.
+ * @param $context
+ *   Array of format_date function arguments and defined variables .
+ *   - settings
+ *   - date_time
+ *   - timezones
+ *   - timestamp
+ *   - type
+ *   - format
+ *   - timezone
+ *   - langcode
+ * @see format_date()
+ */
+function hook_format_date_alter(&$formatted_date, array $context) {
+  $formatted_date .= ' ' . $context['timezone'];
+}
+
+/**
  * @} End of "addtogroup hooks".
  */