Index: includes/MimeMagic.php
===================================================================
--- includes/MimeMagic.php	(revision 103311)
+++ includes/MimeMagic.php	(working copy)
@@ -469,7 +469,7 @@
 			'webp',
 
 			// XML formats we sure hope we recognize reliably
-			'svg',
+			'svg', 'svgz',
 		);
 		return in_array( strtolower( $extension ), $types );
 	}
@@ -661,11 +661,16 @@
 		 */
 		$xml = new XmlTypeCheck( $file );
 		if ( $xml->wellFormed ) {
-			global $wgXMLMimeTypes;
-			if ( isset( $wgXMLMimeTypes[$xml->getRootElement()] ) ) {
-				return $wgXMLMimeTypes[$xml->getRootElement()];
-			} else {
-				return 'application/xml';
+			global $wgXMLMimeTypes, $wgXMLMayBeCompressed;
+			$t = $wgXMLMimeTypes[$xml->getRootElement()];
+			if ( !$xml->compressed ) {
+				if( $t ) {
+					return $t;
+				} else {
+					return 'application/xml';
+				}
+			} elseif ( $wgXMLMayBeCompressed[$t] ) {
+				return $t;
 			}
 		}
 
Index: includes/media/SVGMetadataExtractor.php
===================================================================
--- includes/media/SVGMetadataExtractor.php	(revision 103311)
+++ includes/media/SVGMetadataExtractor.php	(working copy)
@@ -59,13 +59,13 @@
 
 		if ( $size > $wgSVGMetadataCutoff ) {
 			$this->debug( "SVG is $size bytes, which is bigger than $wgSVGMetadataCutoff. Truncating." );
-			$contents = file_get_contents( $source, false, null, -1, $wgSVGMetadataCutoff );
+			$contents = file_get_contents( "compress.zlib://$source", false, null, -1, $wgSVGMetadataCutoff );
 			if ($contents === false) {
 				throw new MWException( 'Error reading SVG file.' );
 			}
 			$this->reader->XML( $contents, null, LIBXML_NOERROR | LIBXML_NOWARNING );
 		} else {
-			$this->reader->open( $source, null, LIBXML_NOERROR | LIBXML_NOWARNING );
+			$this->reader->open( "compress.zlib://$source", null, LIBXML_NOERROR | LIBXML_NOWARNING );
 		}
 
 		$this->metadata['width'] = self::DEFAULT_WIDTH;
Index: includes/DefaultSettings.php
===================================================================
--- includes/DefaultSettings.php	(revision 103311)
+++ includes/DefaultSettings.php	(working copy)
@@ -440,6 +440,11 @@
  */
 $wgMaxUploadSize = 1024*1024*100; # 100MB
 
+$wgXMLMayBeCompressed = array(
+	'image/svg+xml' => true,
+	'application/x-dia-diagram' => true,
+);
+
 /**
  * Point the upload navigation link to an external URL
  * Useful if you want to use a shared repository by default
Index: includes/XmlTypeCheck.php
===================================================================
--- includes/XmlTypeCheck.php	(revision 103311)
+++ includes/XmlTypeCheck.php	(working copy)
@@ -20,6 +20,12 @@
 	public $rootElement = '';
 
 	/**
+	 * Name of file compression type (can be only 'gzip' by now),
+	 * or FALSE if the file is uncompressed.
+	 */
+	public $compressed = false;
+
+	/**
 	 * @param $file string filename
 	 * @param $filterCallback callable (optional)
 	 *        Function to call to do additional custom validity checks from the
@@ -54,6 +60,18 @@
 
 		if ( file_exists( $fname ) ) {
 			$file = fopen( $fname, "rb" );
+			$gz = fread( $file, 2 );
+			if ( $gz == "\x1F\x8B" ) {
+				if ( function_exists( 'gzopen' ) ) {
+					fclose( $file );
+					$this->compressed = 'gzip';
+					$file = gzopen( $fname, "rb" );
+				} else {
+					return;
+				}
+			} else {
+				fseek( $file, 0, SEEK_SET );
+			}
 			if ( $file ) {
 				do {
 					$chunk = fread( $file, 32768 );