Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 26457)
+++ src/wp-includes/formatting.php	(working copy)
@@ -801,6 +801,20 @@
 		}
 
 		$string = strtr($string, $chars);
+		
+		// Removes combining marks using PCRE UTF-8 extension (if available) or a RegEx in UTF-8 bytes
+		if ( 1 === @preg_match( '/\p{L}/u', "\xc3\xa0" ) ) { // Match 'Unicode letter' with 'Latin a with grave'
+			$string = preg_replace( '/[\p{Mn}\p{Me}]/u', '', $string );
+		} else {
+			$combining_marks = array(
+				'/(\xCC[\x80-\xBF])|(\xCD[\x80-\xAF])/', 		// Combining Diacritical Marks (U+0300 ... U+036F) 
+				'/\xE1\xB7[\x80-\xBF]/',						// Combining Diacritical Marks Supplement  (U+1DC0 ... U+1DFF) 
+				'/\xE2\x83[\x90-\xBF]/',						// Combining Diacritical Marks for Symbols (U+20D0 ... U+20FF)
+				'/\xEF\xB8[\xA0-\xAF]/'							// Combining Half Marks (U+FE20 .... U+FE2F)
+			);
+			$string = preg_replace( $combining_marks, '', $string );
+		}
+		
 	} else {
 		// Assume ISO-8859-1 if not UTF-8
 		$chars['in'] = chr(128).chr(131).chr(138).chr(142).chr(154).chr(158)