diff --git a/wp-comments-post.php b/wp-comments-post.php
index 8289bb4414..b781383a5b 100644
--- a/wp-comments-post.php
+++ b/wp-comments-post.php
@@ -30,6 +30,9 @@ if ( empty($status->comment_status) ) {
 } elseif ( in_array($status->post_status, array('draft', 'pending') ) ) {
 	do_action('comment_on_draft', $comment_post_ID);
 	exit;
+} elseif ( 'trash' == $status->post_status ) {
+	do_action('comment_on_trash', $comment_post_ID);
+	exit;
 } else {
 	do_action('pre_comment_on_post', $comment_post_ID);
 }
diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index b9bf8ae9f2..805d2fbae9 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -773,10 +773,12 @@ function wp_count_comments( $post_id = 0 ) {
 	$count = $wpdb->get_results( "SELECT comment_approved, COUNT( * ) AS num_comments FROM {$wpdb->comments} {$where} GROUP BY comment_approved", ARRAY_A );
 
 	$total = 0;
-	$approved = array('0' => 'moderated', '1' => 'approved', 'spam' => 'spam', 'trash' => 'trash');
+	$approved = array('0' => 'moderated', '1' => 'approved', 'spam' => 'spam', 'trash' => 'trash', 'post-trashed' => 'post-trashed');
 	$known_types = array_keys( $approved );
 	foreach( (array) $count as $row_num => $row ) {
-		$total += $row['num_comments'];
+		// Don't count post-trashed toward totals
+		if ( 'post-trashed' != $row['comment_approved'] )
+			$total += $row['num_comments'];
 		if ( in_array( $row['comment_approved'], $known_types ) )
 			$stats[$approved[$row['comment_approved']]] = $row['num_comments'];
 	}
@@ -1178,9 +1180,13 @@ function wp_set_comment_status($comment_id, $comment_status, $wp_error = false)
 	$status = '0';
 	switch ( $comment_status ) {
 		case 'hold':
+		case '0':
+		case 0:
 			$status = '0';
 			break;
 		case 'approve':
+		case '1':
+		case 1:
 			$status = '1';
 			if ( get_option('comments_notify') ) {
 				$comment = get_comment($comment_id);
diff --git a/wp-includes/post.php b/wp-includes/post.php
index f63f364b08..163fec3961 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -1268,6 +1268,8 @@ function wp_trash_post($post_id = 0) {
 	$post['post_status'] = 'trash';
 	wp_insert_post($post);
 
+	wp_trash_post_comments($post_id);
+
 	do_action('trashed_post', $post_id);
 
 	return $post;
@@ -1301,11 +1303,100 @@ function wp_untrash_post($post_id = 0) {
 
 	wp_insert_post($post);
 
+	wp_untrash_post_comments($post_id);
+
 	do_action('untrashed_post', $post_id);
 
 	return $post;
 }
 
+/**
+ * Moves comments for a post to the trash
+ *
+ * @since 2.9.0
+ * @uses do_action() on 'trash_post_comments' before trashing
+ * @uses do_action() on 'trashed_post_comments' after trashing
+ *
+ * @param int $post Post ID or object.
+ * @return mixed False on failure
+ */
+function wp_trash_post_comments($post = null) {
+	global $wpdb;
+
+	$post = get_post($post);
+	if ( empty($post) )
+		return;
+
+	$post_id = $post->ID;
+
+	do_action('trash_post_comments', $post_id);
+
+	$comments = $wpdb->get_results( $wpdb->prepare("SELECT comment_ID, comment_approved FROM $wpdb->comments WHERE comment_post_ID = %d", $post_id) );
+	if ( empty($comments) )
+		return;
+
+	// Cache current status for each comment
+	$statuses = array();
+	foreach ( $comments as $comment )
+		$statuses[$comment->comment_ID] = $comment->comment_approved;
+	add_post_meta($post_id, '_wp_trash_meta_comments_status', $statuses);
+
+	// Set status for all comments to post-trashed
+	$result = $wpdb->update($wpdb->comments, array('comment_approved' => 'post-trashed'), array('comment_post_ID' => $post_id));
+
+	clean_comment_cache( array_keys($statuses) );
+
+	do_action('trashed_post_comments', $post_id, $statuses);
+
+	return $result;
+}
+
+/**
+ * Restore comments for a post from the trash
+ *
+ * @since 2.9.0
+ * @uses do_action() on 'untrash_post_comments' before trashing
+ * @uses do_action() on 'untrashed_post_comments' after trashing
+ *
+ * @param int $post Post ID or object.
+ * @return mixed False on failure
+ */
+function wp_untrash_post_comments($post = null) {
+	global $wpdb;
+
+	$post = get_post($post);
+	if ( empty($post) )
+		return;
+
+	$post_id = $post->ID;
+
+	$statuses = get_post_meta($post_id, '_wp_trash_meta_comments_status', true);
+
+	if ( empty($statuses) )
+		return true;
+
+	do_action('untrash_post_comments', $post_id);
+
+	// Restore each comment to its original status
+	$group_by_status = array();
+	foreach ( $statuses as $comment_id => $comment_status )
+		$group_by_status[$comment_status][] = $comment_id;
+
+	foreach ( $group_by_status as $status => $comments ) {
+		// Sanity check. This shouldn't happen.
+		if ( 'post-trashed' == $status )
+			$status = '0';
+		$comments_in = implode( "', '", $comments );
+		$wpdb->query( "UPDATE $wpdb->comments SET comment_approved = '$status' WHERE comment_ID IN ('" . $comments_in . "')" );
+	}
+
+	clean_comment_cache( array_keys($statuses) );
+
+	delete_post_meta($post_id, '_wp_trash_meta_comments_status');
+
+	do_action('untrashed_post_comments', $post_id);
+}
+
 /**
  * Retrieve the list of categories for a post.
  *