Index: languages/Language.php
===================================================================
--- languages/Language.php	(revision 105772)
+++ languages/Language.php	(working copy)
@@ -132,6 +132,25 @@
 		'hijri-calendar-m10', 'hijri-calendar-m11', 'hijri-calendar-m12'
 	);
 
+	static public $mBCP47Normalizations = array(
+		'simple'	=> 'en-x-simple',
+		'als'		=> 'gsw',	// als is now ISO gsw, but might later be moved to aeg
+		'bat-smg'	=> 'sgs',
+		'be-x-old'	=> 'be-tarask',
+		'cbk-zam'	=> 'cbk',	// Family name
+		'ksh'		=> 'gem',	// Family name. No ripuarian macrolanguage code, ksh too specific
+		'fiu-vro'	=> 'vro',
+		'map-bms'	=> 'map',	// Family name. No Banyumasan langaguage code
+		'ms'		=> 'zsm',
+		'nds-nl'	=> 'nl',	// A collection of dutch low saxon dialects
+		'no'		=> 'nb',
+		'roa-rup'	=> 'rup',
+		'roa-tara'	=> 'roa',	// Family name, no Tarantino language code
+		'sq'		=> 'als',
+		'zh-classical'	=> 'lzh',
+		'zh-min-nan'	=> 'nan'
+	);
+
 	/**
 	 * Get a cached language object for a given language code
 	 * @param $code String
@@ -690,6 +709,22 @@
 	}
 
 	/**
+	 * Get the BCP-47 tag of a MediaWiki language code
+	 *
+	 * http://tools.ietf.org/rfc/bcp/bcp47.txt
+	 * http://en.wikipedia.org/wiki/IETF_language_tag
+	 *
+	 * @param $code String Language code.
+	 * @return String bcp-47 code. If unknown, fallback to $code
+	 */
+	public static function getBCP47LanguageTag( $code ) {
+		if( array_key_exists( $code, self::$mBCP47Normalizations ) ) {
+			return self::$mBCP47Normalizations[$code];
+		}
+		return $code;
+	}
+
+	/**
 	 * Get a message from the MediaWiki namespace.
 	 *
 	 * @param $msg String: message name
@@ -3446,7 +3481,7 @@
 	 * @return string
 	 */
 	function getCode() {
-		return $this->mCode;
+		return Language::getBCP47LanguageTag($this->mCode);
 	}
 
 	/**