Index: src/wp-includes/feed-rss2-comments.php
===================================================================
--- src/wp-includes/feed-rss2-comments.php	(revision 42813)
+++ src/wp-includes/feed-rss2-comments.php	(working copy)
@@ -34,16 +34,26 @@
 <channel>
 	<title>
 	<?php
+	$page_title = '';
 	if ( is_singular() ) {
 		/* translators: Comments feed title. 1: Post title */
-		printf( ent2ncr( __( 'Comments on: %s' ) ), get_the_title_rss() );
+		$page_title = sprintf( ent2ncr( __( 'Comments on: %s' ) ), get_the_title_rss() );
 	} elseif ( is_search() ) {
 		/* translators: Comments feed title. 1: Site name, 2: Search query */
-		printf( ent2ncr( __( 'Comments for %1$s searching on %2$s' ) ), get_bloginfo_rss( 'name' ), get_search_query() );
+		$page_title = sprintf( ent2ncr( __( 'Comments for %1$s searching on %2$s' ) ), get_bloginfo_rss( 'name' ), get_search_query() );
 	} else {
 		/* translators: Comments feed title. 1: Site name */
-		printf( ent2ncr( __( 'Comments for %s' ) ), get_wp_title_rss() );
+		$page_title = sprintf( ent2ncr( __( 'Comments for %s' ) ), get_bloginfo_rss( 'name' ) . get_wp_title_rss() );
 	}
+
+	/**
+	 * Filter the page title for the RSS2 comments feed.
+	 *
+	 * @since 4.9
+	 *
+	 * @param string $page_title RSS2 comments feed page title.
+	 */
+	echo apply_filters( 'rss_comments_page_title', $page_title, get_the_title_rss() );
 	?>
 	</title>
 	<atom:link href="<?php self_link(); ?>" rel="self" type="application/rss+xml" />
@@ -78,21 +88,32 @@
 	if ( have_comments() ) :
 		while ( have_comments() ) :
 			the_comment();
-			$comment_post = $GLOBALS['post'] = get_post( $comment->comment_post_ID );
+			$comment_post   = $GLOBALS['post'] = get_post( $comment->comment_post_ID );
 			?>
 			<item>
 				<title>
 				<?php
+				$item_title = '';
 				if ( ! is_singular() ) {
 					$title = get_the_title( $comment_post->ID );
 					/** This filter is documented in wp-includes/feed.php */
 					$title = apply_filters( 'the_title_rss', $title );
 					/* translators: Individual comment title. 1: Post title, 2: Comment author name */
-					printf( ent2ncr( __( 'Comment on %1$s by %2$s' ) ), $title, get_comment_author_rss() );
+					$item_title = sprintf( ent2ncr( __( 'Comment on %1$s by %2$s' ) ), $title, get_comment_author_rss() );
 				} else {
 					/* translators: Comment author title. 1: Comment author name */
-					printf( ent2ncr( __( 'By: %s' ) ), get_comment_author_rss() );
+					$item_title = sprintf( ent2ncr( __( 'By: %s' ) ), get_comment_author_rss() );
 				}
+
+				/**
+				 * Filter the title to use for an item in an RSS2 comments feed.
+				 *
+				 * @since 4.9
+				 *
+				 * @param string $item_title   RSS2 comments feed item title.
+				 * @param object $comment_post Comment post object.
+				 */
+				echo apply_filters( 'rss_comments_item_title', $item_title, $comment_post );
 				?>
 				</title>
 				<link><?php comment_link(); ?></link>