Index: .htaccess
===================================================================
RCS file: /cvs/drupal/drupal/.htaccess,v
retrieving revision 1.109
diff -u -p -u -p -r1.109 .htaccess
--- .htaccess	5 May 2010 06:15:59 -0000	1.109
+++ .htaccess	22 Sep 2010 16:40:14 -0000
@@ -109,6 +109,31 @@ DirectoryIndex index.php index.html inde
   RewriteCond %{REQUEST_FILENAME} !-d
   RewriteCond %{REQUEST_URI} !=/favicon.ico
   RewriteRule ^ index.php [L]
+
+  # Rules to correctly serve gzip compressed CSS and JS files.
+  # Requires both mod_rewrite and mod_headers to be enabled.
+  <IfModule mod_headers.c>
+    # Serve gzip compressed CSS files if they exist and the client accepts gzip.
+    RewriteCond %{HTTP:Accept-encoding} gzip
+    RewriteCond %{REQUEST_FILENAME}\.gz -s
+    RewriteRule ^(.*)\.css $1\.css\.gz [QSA]
+
+    # Serve gzip compressed JS files if they exist and the client accepts gzip.
+    RewriteCond %{HTTP:Accept-encoding} gzip
+    RewriteCond %{REQUEST_FILENAME}\.gz -s
+    RewriteRule ^(.*)\.js $1\.js\.gz [QSA]
+
+    # Serve correct content types, and prevent mod_deflate double gzip.
+    RewriteRule \.css\.gz$ - [T=text/css,E=no-gzip:1]
+    RewriteRule \.js\.gz$ - [T=text/javascript,E=no-gzip:1]
+
+    <FilesMatch "(\.js\.gz|\.css\.gz)$">
+      # Serve correct encoding type.
+      Header append Content-Encoding gzip
+      # Force proxies to cache gzipped & non-gzipped css/js files separately.
+      Header append Vary Accept-Encoding
+    </FilesMatch>
+  </IfModule>
 </IfModule>
 
 # $Id: .htaccess,v 1.109 2010/05/05 06:15:59 webchick Exp $
Index: INSTALL.txt
===================================================================
RCS file: /cvs/drupal/drupal/INSTALL.txt,v
retrieving revision 1.83
diff -u -p -u -p -r1.83 INSTALL.txt
--- INSTALL.txt	22 Sep 2010 01:49:17 -0000	1.83
+++ INSTALL.txt	22 Sep 2010 16:40:14 -0000
@@ -44,6 +44,9 @@ OPTIONAL TASKS
   Clean URLs support on IIS, see "Using Clean URLs with IIS"
   (http://drupal.org/node/3854) in the Drupal handbook.
 
+- To serve gzip compressed CSS and JS files on an Apache web server, you will
+  need the mod_headers module and the ability to use local .htaccess files.
+
 - Various Drupal features require that the web server process (for
   example, httpd) be able to initiate outbound connections. This is usually
   possible, but some hosting providers or server configurations forbid such
Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1223
diff -u -p -u -p -r1.1223 common.inc
--- includes/common.inc	22 Sep 2010 03:24:09 -0000	1.1223
+++ includes/common.inc	22 Sep 2010 16:40:14 -0000
@@ -3253,6 +3253,15 @@ function drupal_build_css_cache($css) {
     if (!file_exists($uri) && !file_unmanaged_save_data($data, $uri, FILE_EXISTS_REPLACE)) {
       return FALSE;
     }
+    // If CSS gzip compression is enabled, clean URLs are enabled (which means
+    // that rewrite rules are working) and the zlib extension is available then
+    // create a gzipped version of this file. This file is served conditionally
+    // to browsers that accept gzip using .htaccess rules.
+    if (variable_get('css_gzip_compression', TRUE) && variable_get('clean_url', 0) && extension_loaded('zlib')) {
+      if (!file_exists($uri . '.gz') && !file_unmanaged_save_data(gzencode($data, 9, FORCE_GZIP), $uri . '.gz', FILE_EXISTS_REPLACE)) {
+        return FALSE;
+      }
+    }
     // Save the updated map.
     $map[$key] = $uri;
     variable_set('drupal_css_cache_files', $map);
@@ -4448,9 +4457,18 @@ function drupal_build_js_cache($files) {
     $uri = $jspath . '/' . $filename;
     // Create the JS file.
     file_prepare_directory($jspath, FILE_CREATE_DIRECTORY);
-    if (!file_unmanaged_save_data($contents, $uri, FILE_EXISTS_REPLACE)) {
+    if (!file_exists($uri) && !file_unmanaged_save_data($contents, $uri, FILE_EXISTS_REPLACE)) {
       return FALSE;
     }
+    // If JS gzip compression is enabled, clean URLs are enabled (which means
+    // that rewrite rules are working) and the zlib extension is available then
+    // create a gzipped version of this file. This file is served conditionally
+    // to browsers that accept gzip using .htaccess rules.
+    if (variable_get('js_gzip_compression', TRUE) && variable_get('clean_url', 0) && extension_loaded('zlib')) {
+      if (!file_exists($uri . '.gz') && !file_unmanaged_save_data(gzencode($contents, 9, FORCE_GZIP), $uri . '.gz', FILE_EXISTS_REPLACE)) {
+        return FALSE;
+      }
+    }
     $map[$key] = $uri;
     variable_set('drupal_js_cache_files', $map);
   }
Index: sites/default/default.settings.php
===================================================================
RCS file: /cvs/drupal/drupal/sites/default/default.settings.php,v
retrieving revision 1.50
diff -u -p -u -p -r1.50 default.settings.php
--- sites/default/default.settings.php	8 Aug 2010 19:35:49 -0000	1.50
+++ sites/default/default.settings.php	22 Sep 2010 16:40:14 -0000
@@ -378,6 +378,21 @@ ini_set('session.cookie_lifetime', 20000
 # $conf['omit_vary_cookie'] = TRUE;
 
 /**
+ * CSS/JS aggregated file gzip compression:
+ *
+ * By default, when CSS or JS aggregation and clean URLs are enabled Drupal will
+ * store a gzip compressed (.gz) copy of the aggregated files. If this file is
+ * available then rewrite rules in the default .htaccess file will serve these
+ * files to browsers that accept gzip encoded content. This allows pages to load
+ * faster for these users and has minimal impact on server load. If you are
+ * using a webserver other than Apache httpd, or a caching reverse proxy that is
+ * configured to cache and compress these files itself you may want to uncomment
+ * one or both of the below lines, which will prevent gzip files being stored.
+ */
+# $conf['css_gzip_compression'] = FALSE;
+# $conf['js_gzip_compression'] = FALSE;
+
+/**
  * String overrides:
  *
  * To override specific strings on your site with or without enabling locale