Index: wp-includes/class-wp-editor.php
===================================================================
--- wp-includes/class-wp-editor.php	(revision 23178)
+++ wp-includes/class-wp-editor.php	(working copy)
@@ -327,7 +327,12 @@
 							{selector : 'p,h1,h2,h3,h4,h5,h6,td,th,div,ul,ol,li', styles : {textAlign : 'right'}},
 							{selector : 'img,table', classes : 'alignright'}
 						],
-						strikethrough : {inline : 'del'}
+						strikethrough : {inline : 'del'},
+						removeformat : [
+							{selector : 'b,strong,em,i,font,u,strike,del,ins,small,big,s', remove : 'all', split : true, expand : false, block_expand : true, deep : true},
+							{selector : 'span', attributes : ['style', 'class'], remove : 'empty', split : true, expand : false, deep : true},
+							{selector : '*', attributes : ['style', 'class'], split : false, expand : false, deep : true}
+						]
 					}",
 					'relative_urls' => false,
 					'remove_script_host' => false,