diff --git a/date_popup/date_popup.js b/date_popup/date_popup.js
index bbf25e2..f38dcb5 100644
--- a/date_popup/date_popup.js
+++ b/date_popup/date_popup.js
@@ -14,6 +14,14 @@
           $(this).click(function(){
             $(this).focus();
           });
+          if (datePopup.settings.syncEndDate) {
+            $('.start-date-wrapper').each(function(){
+              var start_date_wrapper = this;
+              $(this).find('input:eq(0)').change(function(){
+                $(start_date_wrapper).next('.end-date-wrapper').find('input:eq(0)').val($(this).val());
+              });
+            });
+          }
           break;
 
         case 'timeEntry':
diff --git a/date_popup/date_popup.module b/date_popup/date_popup.module
index e91cc8a..db95168 100644
--- a/date_popup/date_popup.module
+++ b/date_popup/date_popup.module
@@ -394,6 +394,10 @@ function date_popup_process_date_part(&$element) {
     'fromTo' => isset($fromto),
   );
 
+  if (!empty($element['#instance'])) {
+    $settings['syncEndDate'] = $element['#instance']['settings']['default_value2'] == 'sync';
+  }
+
   // Create a unique id for each set of custom settings.
   $id = date_popup_js_settings_id($element['#id'], 'datepicker', $settings);
 
@@ -801,6 +805,14 @@ function theme_date_popup($vars) {
 }
 
 /**
+ * Implements hook_date_field_instance_settings_form_alter().
+ */
+function date_popup_date_field_instance_settings_form_alter(&$form, $context) {
+  // Add an extra option to sync the end date with the start date.
+  $form['default_value2']['#options']['sync'] = t('Sync with start date');
+}
+
+/**
  * Implements hook_menu().
  */
 function date_popup_menu() {