diff --git a/django/contrib/admin/static/admin/js/SelectBox.js b/django/contrib/admin/static/admin/js/SelectBox.js
index f28c861513..db3206ccf5 100644
--- a/django/contrib/admin/static/admin/js/SelectBox.js
+++ b/django/contrib/admin/static/admin/js/SelectBox.js
@@ -16,7 +16,10 @@ var SelectBox = {
         for (var i = 0, j = SelectBox.cache[id].length; i < j; i++) {
             var node = SelectBox.cache[id][i];
             if (node.displayed) {
-                box.options[box.options.length] = new Option(node.text, node.value, false, false);
+                var new_option = new Option(node.text, node.value, false, false);
+                // Shows a tooltip when hovering over the option
+                new_option.setAttribute("title", node.text);
+                box.options[box.options.length] = new_option;
             }
         }
     },
diff --git a/tests/admin_widgets/tests.py b/tests/admin_widgets/tests.py
index 7d2f70f69b..0aa6129295 100644
--- a/tests/admin_widgets/tests.py
+++ b/tests/admin_widgets/tests.py
@@ -699,7 +699,12 @@ class HorizontalVerticalFilterSeleniumFirefoxTests(AdminSeleniumWebDriverTestCas
         self.assertActiveButtons(mode, field_name, False, False, True, False)
 
         # Choose some options ------------------------------------------------
-        self.get_select_option(from_box, str(self.lisa.id)).click()
+        from_lisa_select_option = self.get_select_option(from_box, str(self.lisa.id))
+
+        # Check the title attribute is there for tool tips: ticket #20821
+        self.assertEqual(from_lisa_select_option.get_attribute('title'), from_lisa_select_option.get_attribute('text'))
+
+        from_lisa_select_option.click()
         self.get_select_option(from_box, str(self.jason.id)).click()
         self.get_select_option(from_box, str(self.bob.id)).click()
         self.get_select_option(from_box, str(self.john.id)).click()
@@ -714,6 +719,10 @@ class HorizontalVerticalFilterSeleniumFirefoxTests(AdminSeleniumWebDriverTestCas
                         [str(self.lisa.id), str(self.bob.id),
                          str(self.jason.id), str(self.john.id)])
 
+        # Check the tooltip is still there after moving: ticket #20821
+        to_lisa_select_option = self.get_select_option(to_box, str(self.lisa.id))
+        self.assertEqual(to_lisa_select_option.get_attribute('title'), to_lisa_select_option.get_attribute('text'))
+
         # Remove some options -------------------------------------------------
         self.get_select_option(to_box, str(self.lisa.id)).click()
         self.get_select_option(to_box, str(self.bob.id)).click()