Index: wp-includes/js/wplink.js
===================================================================
--- wp-includes/js/wplink.js	(revision 23301)
+++ wp-includes/js/wplink.js	(working copy)
@@ -285,6 +285,7 @@
 			// Leave the new tab setting as-is.
 			inputs.url.val('http://');
 			inputs.title.val('');
+			inputs.search.val( tinyMCEPopup.editor.selection.getContent( { format: 'text' } ) ).trigger( 'keyup' );
 
 			// Update save prompt.
 			inputs.submit.val( wpLinkL10n.save );