Index: src/wp-includes/author-template.php
===================================================================
--- src/wp-includes/author-template.php	(revision 28671)
+++ src/wp-includes/author-template.php	(working copy)
@@ -336,7 +336,7 @@
 		'orderby' => 'name', 'order' => 'ASC', 'number' => '',
 		'optioncount' => false, 'exclude_admin' => true,
 		'show_fullname' => false, 'hide_empty' => true,
-		'feed' => '', 'feed_image' => '', 'feed_type' => '', 'echo' => true,
+		'feed' => '', 'feed_image' => '', 'feed_type' => '', 'post_type' => '', 'echo' => true,
 		'style' => 'list', 'html' => true, 'exclude' => '', 'include' => ''
 	);
 
@@ -348,8 +348,14 @@
 	$query_args['fields'] = 'ids';
 	$authors = get_users( $query_args );
 
+	if( ! empty( $args['post_type'] ) ) {
+		$post_type = "post_type = '{$args['post_type']}' ";
+	} else {
+		$post_type = "";
+	}
+
 	$author_count = array();
-	foreach ( (array) $wpdb->get_results( "SELECT DISTINCT post_author, COUNT(ID) AS count FROM $wpdb->posts WHERE post_type = 'post' AND " . get_private_posts_cap_sql( 'post' ) . " GROUP BY post_author" ) as $row ) {
+	foreach ( (array) $wpdb->get_results( "SELECT DISTINCT post_author, COUNT(ID) AS count FROM $wpdb->posts WHERE $post_type" . get_private_posts_cap_sql( 'any' ) . " GROUP BY post_author" ) as $row ) {
 		$author_count[$row->post_author] = $row->count;
 	}
 	foreach ( $authors as $author_id ) {
@@ -440,7 +446,7 @@
 	global $wpdb;
 
 	if ( false === ( $is_multi_author = get_transient( 'is_multi_author' ) ) ) {
-		$rows = (array) $wpdb->get_col("SELECT DISTINCT post_author FROM $wpdb->posts WHERE post_type = 'post' AND post_status = 'publish' LIMIT 2");
+		$rows = (array) $wpdb->get_col("SELECT DISTINCT post_author FROM $wpdb->posts WHERE post_status = 'publish' LIMIT 2");
 		$is_multi_author = 1 < count( $rows ) ? 1 : 0;
 		set_transient( 'is_multi_author', $is_multi_author );
 	}
Index: src/wp-includes/post.php
===================================================================
--- src/wp-includes/post.php	(revision 28671)
+++ src/wp-includes/post.php	(working copy)
@@ -5238,7 +5238,7 @@
 		$cap = $post_type_obj->cap->read_private_posts;
 	}
 
-	if ( $full ) {
+	if ( $full && 'any' != $post_type ) {
 		if ( null === $post_author ) {
 			$sql = $wpdb->prepare( 'WHERE post_type = %s AND ', $post_type );
 		} else {
Index: src/wp-includes/user.php
===================================================================
--- src/wp-includes/user.php	(revision 28671)
+++ src/wp-includes/user.php	(working copy)
@@ -256,10 +256,10 @@
  * @param int $userid User ID.
  * @return int Amount of posts user has written.
  */
-function count_user_posts($userid) {
+function count_user_posts( $userid, $post_type = false ) {
 	global $wpdb;
 
-	$where = get_posts_by_author_sql('post', true, $userid);
+	$where = get_posts_by_author_sql( $post_type, true, $userid );
 
 	$count = $wpdb->get_var( "SELECT COUNT(*) FROM $wpdb->posts $where" );