Index: src/wp-includes/capabilities.php
===================================================================
--- src/wp-includes/capabilities.php	(revision 41309)
+++ src/wp-includes/capabilities.php	(working copy)
@@ -862,3 +862,59 @@

 	return $allcaps;
 }
+
+function wp_maybe_grant_customize_changeset_caps( $allcaps, $caps, $args, $user ) {
+	global $post_type_meta_caps;
+
+	$changeset_post_type = get_post_type_object( 'customize_changeset' );
+
+	// Do something only when the capability type is the default.
+	if ( ( $changeset_post_type instanceof WP_Post_Type ) && ( 'customize_changeset' === $changeset_post_type->capability_type ) ) {
+		$changeset_caps = get_object_vars( $changeset_post_type->cap );
+
+		// Reduce $changeset_caps to post type primitives.
+		unset( $changeset_caps['read'] );
+		foreach ( $changeset_caps as $key => $cap ) {
+			if ( isset( $post_type_meta_caps[ $cap ] ) ) {
+				unset( $changeset_caps[ $key ] );
+			}
+		}
+
+		// Do something only when at least one of the required $caps is a changeset primitive.
+		if ( array_intersect( array_values( $changeset_caps ), $caps ) ) {
+			// All changeset capabilities were previously 'customize'.
+			$user_can_args = array( $user->ID, 'customize' );
+
+			/*
+			 * For compatibility with cases when 'customize' was passed a post
+			 * ID, also pass $args if the object ID corresponds to a changeset.
+			 */
+			if (
+				isset( $args[2] )
+				&& is_numeric( $args[2] )
+				&& ( intval( $args[2] ) > 0 )
+				&& ( 'customize_changeset' === get_post_type( $args[2] ) )
+			) {
+				$user_can_args = array_merge( $user_can_args, array_slice( $args, 2 ) );
+			}
+
+			/*
+			 * Avoid an infinite loop if 'customize' has been mapped to a
+			 * changeset primitive. But note that if 'customize' *is* mapped to
+			 * any changeset primitives, then this function won't be hooked in
+			 * to dynamically grant the user those primitives.
+			 */
+			remove_filter( 'user_has_cap', 'wp_maybe_grant_customize_changeset_caps', 1, 4 );
+			$user_can = call_user_func_array( 'user_can', $user_can_args );
+			add_filter( 'user_has_cap', 'wp_maybe_grant_customize_changeset_caps', 1, 4 );
+
+			$allcaps = array_merge(
+				$allcaps,
+				array_fill_keys( array_values( $changeset_caps ), $user_can )
+			);
+		}
+	}
+
+	return $allcaps;
+}
+add_filter( 'user_has_cap', 'wp_maybe_grant_customize_changeset_caps', 1, 4 );
Index: src/wp-includes/post.php
===================================================================
--- src/wp-includes/post.php	(revision 41309)
+++ src/wp-includes/post.php	(working copy)
@@ -176,23 +176,6 @@
 		'delete_with_user' => false,
 		'supports' => array( 'title', 'author' ),
 		'capability_type' => 'customize_changeset',
-		'capabilities' => array(
-			'create_posts' => 'customize',
-			'delete_others_posts' => 'customize',
-			'delete_post' => 'customize',
-			'delete_posts' => 'customize',
-			'delete_private_posts' => 'customize',
-			'delete_published_posts' => 'customize',
-			'edit_others_posts' => 'customize',
-			'edit_post' => 'customize',
-			'edit_posts' => 'customize',
-			'edit_private_posts' => 'customize',
-			'edit_published_posts' => 'do_not_allow',
-			'publish_posts' => 'customize',
-			'read' => 'read',
-			'read_post' => 'customize',
-			'read_private_posts' => 'customize',
-		),
 	) );

 	register_post_status( 'publish', array(