//Custom markup for Comments
function my_custom_comments($comment, $args, $depth) {
   $GLOBALS['comment'] = $comment;
   echo '<li '; comment_class(); echo '>';

   if ($comment->comment_approved == '0') :
      echo '<em>' . _e('Your comment is awaiting moderation.') . '</em>';
   endif;
    //Start Custom Markup
    comment_text();
   //End Custom Markup
}