diff --git a/wp-includes/classes.php b/wp-includes/classes.php
index 65bf85a1f6..79709dbf15 100644
--- a/wp-includes/classes.php
+++ b/wp-includes/classes.php
@@ -73,7 +73,7 @@ class retrospam_mgr {
 }
 
 class WP {
-	var $public_query_vars = array('m', 'p', 'posts', 'w', 'cat', 'withcomments', 's', 'search', 'exact', 'sentence', 'debug', 'calendar', 'page', 'paged', 'more', 'tb', 'pb', 'author', 'order', 'orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'feed', 'author_name', 'static', 'pagename', 'page_id', 'error', 'comments_popup', 'attachment', 'attachment_id', 'subpost', 'subpost_id', 'preview');
+	var $public_query_vars = array('m', 'p', 'posts', 'w', 'cat', 'withcomments', 's', 'search', 'exact', 'sentence', 'debug', 'calendar', 'page', 'paged', 'more', 'tb', 'pb', 'author', 'order', 'orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'feed', 'author_name', 'static', 'pagename', 'page_id', 'error', 'comments_popup', 'attachment', 'attachment_id', 'subpost', 'subpost_id', 'preview', 'robots');
 
 	var $private_query_vars = array('posts_per_page', 'posts_per_archive_page', 'what_to_show', 'showposts', 'nopaging', 'post_type');
 	var $extra_query_vars = array();
diff --git a/wp-includes/default-filters.php b/wp-includes/default-filters.php
index f45b3f4a72..0c5ad99d70 100644
--- a/wp-includes/default-filters.php
+++ b/wp-includes/default-filters.php
@@ -94,4 +94,5 @@ add_action('do_feed_rss', 'do_feed_rss', 10, 1);
 add_action('do_feed_rss2', 'do_feed_rss2', 10, 1);
 add_action('do_feed_atom', 'do_feed_atom', 10, 1);
 add_action('do_pings', 'do_all_pings', 10, 1);
+add_action('do_robots', 'do_robots');
 ?>
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index e003d8d8ee..042dfa5bed 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -1655,6 +1655,16 @@ function do_feed_atom() {
 	load_template(ABSPATH . 'wp-atom.php');
 }
 
+function do_robots() {
+	if ( '1' != get_option('blog_public') ) {
+		echo "User-agent: *\n";
+		echo "Disallow: /\n";
+	} else {
+		echo "User-agent: *\n";
+		echo "Disallow:\n";
+	}
+}
+
 function is_blog_installed() {
 	global $wpdb;
 	$wpdb->hide_errors();
diff --git a/wp-includes/query.php b/wp-includes/query.php
index e6c82988a9..79cd3d8125 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -157,6 +157,12 @@ function is_preview() {
 	return $wp_query->is_preview;
 }
 
+function is_robots() {
+	global $wp_query;
+
+	return $wp_query->is_robots;
+}
+
 function is_search () {
 	global $wp_query;
 
@@ -272,6 +278,7 @@ class WP_Query {
 	var $is_comments_popup = false;
 	var $is_admin = false;
 	var $is_attachment = false;
+	var $is_robots = false;
 
 	function init_query_flags() {
 		$this->is_single = false;
@@ -292,6 +299,7 @@ class WP_Query {
 		$this->is_paged = false;
 		$this->is_admin = false;
 		$this->is_attachment = false;
+		$this->is_robots = false;
 	}
 
 	function init () {
@@ -321,6 +329,11 @@ class WP_Query {
 			$this->query_vars = $qv;
 		}
 
+		if ( ! empty($qv['robots']) ) {
+			$this->is_robots = true;
+			return;
+		}
+
 		if ('404' == $qv['error']) {
 			$this->is_404 = true;
 			if ( !empty($query) ) {
diff --git a/wp-includes/rewrite.php b/wp-includes/rewrite.php
index ffc5d55d67..48fa20b80f 100644
--- a/wp-includes/rewrite.php
+++ b/wp-includes/rewrite.php
@@ -696,6 +696,9 @@ class WP_Rewrite {
 			return $rewrite;
 		}
 
+		// robots.txt
+		$robots_rewrite = array('robots.txt$' => $this->index . '?robots=1');
+
 		// Post
 		$post_rewrite = $this->generate_rewrite_rules($this->permalink_structure, EP_PERMALINK);
 		$post_rewrite = apply_filters('post_rewrite_rules', $post_rewrite);
@@ -730,7 +733,7 @@ class WP_Rewrite {
 		$page_rewrite = apply_filters('page_rewrite_rules', $page_rewrite);
 
 		// Put them together.
-		$this->rules = array_merge($page_rewrite, $root_rewrite, $comments_rewrite, $search_rewrite, $category_rewrite, $author_rewrite, $date_rewrite, $post_rewrite, $this->extra_rules);
+		$this->rules = array_merge($robots_rewrite, $page_rewrite, $root_rewrite, $comments_rewrite, $search_rewrite, $category_rewrite, $author_rewrite, $date_rewrite, $post_rewrite, $this->extra_rules);
 
 		do_action('generate_rewrite_rules', array(&$this));
 		$this->rules = apply_filters('rewrite_rules_array', $this->rules);
diff --git a/wp-includes/template-loader.php b/wp-includes/template-loader.php
index 3f8299f434..ea7ae82d21 100644
--- a/wp-includes/template-loader.php
+++ b/wp-includes/template-loader.php
@@ -1,7 +1,10 @@
 <?php
 if ( defined('WP_USE_THEMES') && constant('WP_USE_THEMES') ) {
 	do_action('template_redirect');
-	if ( is_feed() ) {
+	if ( is_robots() ) {
+		do_action('do_robots');
+		exit;
+	} else if ( is_feed() ) {
 		do_feed();
 		exit;
 	} else if ( is_trackback() ) {
@@ -55,7 +58,10 @@ if ( defined('WP_USE_THEMES') && constant('WP_USE_THEMES') ) {
 	}
 } else {
 	// Process feeds and trackbacks even if not using themes.
-	if ( is_feed() ) {
+	if ( is_robots() ) {
+		do_action('do_robots');
+		exit;
+	} else if ( is_feed() ) {
 		do_feed();
 		exit;
 	} else if ( is_trackback() ) {