diff --git commands/core/core.drush.inc commands/core/core.drush.inc
index 1c0043f..5f958c9 100644
--- commands/core/core.drush.inc
+++ commands/core/core.drush.inc
@@ -137,6 +137,7 @@ function core_drush_command() {
       'site_name' => 'Defaults to installsite',
       'site_mail' => 'From: for system mailings. Defaults to admin@example.com',
       'sites-subdir' => "Name of directory under 'sites' which should be created if needed. Defaults to 'default'",
+      'max-mem' => 'Set the memory_limit for PHP.',
     ),
     'examples' => array(
       'installsite expert --locale=uk' => '(Re)install using the expert install profile. Set default language to Ukranian.',
diff --git a/commands/core/installsite.drush.inc b/commands/core/installsite.drush.inc
index 30ab605..891b67a 100644
--- commands/core/installsite.drush.inc
+++ commands/core/installsite.drush.inc
@@ -75,8 +75,13 @@ function drush_core_pre_installsite() {
 
 function drush_core_installsite($profile = 'default') {
   require_once('install.php');
+  
+  $maxmem = drush_get_option('max-mem', NULL);
+  if(NULL != $maxmem) {
+    ini_set('memory_limit', $maxmem);
+  }
 
   $db_spec = drush_core_installsite_db_spec();
 
   $account_pass = drush_get_option('account_pass', 'admin');