diff -u b/includes/bootstrap.inc b/includes/bootstrap.inc
--- b/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -724,6 +724,7 @@
   // set to 'https'.
   // Trusting these headers is a potential security risk so we only do so if
   // $conf['reverse_proxy'] has been set.
+  $scheme_rewrite = FALSE;
   if (variable_get('reverse_proxy', 0)) {
     $reverse_proxy_proto_header = variable_get('reverse_proxy_proto_header', 'HTTP_X_FORWARDED_PROTO');
     if (isset($_SERVER[$reverse_proxy_proto_header]) && strtolower($_SERVER[$reverse_proxy_proto_header]) == 'https') {
@@ -731,10 +732,14 @@
       // To ensure that third-party code continues working.
       // They should however implement support for X-Forwarded-Proto themselves.
       $_SERVER['HTTPS'] = 'on';
+      $scheme_rewrite = (boolean) variable_get('reverse_proxy_proto_change', FALSE);
     }
   }
 
   if (isset($base_url)) {
+    if ($scheme_rewrite) {
+      $base_url = $is_https ? str_replace('http://', 'https://', $base_url) : str_replace('https://', 'http://', $base_url);
+    }
     // Parse fixed base URL from settings.php.
     $parts = parse_url($base_url);
     if (!isset($parts['path'])) {
diff -u b/sites/default/default.settings.php b/sites/default/default.settings.php
--- b/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -263,9 +263,6 @@
  *
  * It is not allowed to have a trailing slash; Drupal will add it
  * for you.
- *
- * If you are using a reverse proxy as a crypto offloader, you must ensure that
- * this variable is commented.
  */
 # $base_url = 'http://www.example.com';  // NO trailing slash!
 
@@ -387,6 +384,10 @@
  * $_SERVER['REMOTE_ADDR'] variable directly in settings.php.
  * Be aware, however, that it is likely that this would allow IP
  * address spoofing unless more advanced precautions are taken.
+ *
+ * Enable this setting to get Drupal to determine the scheme to use for
+ * generated URLs using the value of the X-Forwarded-Proto header (or
+ * $conf['reverse_proxy_proto_header'] if set).
  */
 # $conf['reverse_proxy'] = TRUE;
 
@@ -409,6 +410,13 @@
 # $conf['reverse_proxy_proto_header'] = 'HTTP_X_FORWARDED_PROTO';
 
 /**
+ * Set this value if you want Drupal to modify the scheme of the $base_url
+ * based on the value of the X-Forwarded-Proto header (or
+ * $conf['reverse_proxy_proto_header'] if set).
+ */
+# $conf['reverse_proxy_proto_change'] = TRUE;
+
+/**
  * Page caching:
  *
  * By default, Drupal sends a "Vary: Cookie" HTTP header for anonymous page