diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
index a0d3fe805d..d0333c61c4 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
@@ -270,6 +270,10 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 
 		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );
 
+		if ( ! empty( $request['tax_relation'] ) ) {
+			$query_args['tax_query'] = array( 'relation' => $request['tax_relation'] );
+		}
+
 		foreach ( $taxonomies as $taxonomy ) {
 			$base        = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
 			$tax_exclude = $base . '_exclude';
@@ -2531,6 +2535,14 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 
 		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );
 
+		if ( ! empty( $taxonomies ) ) {
+			$query_params['tax_relation'] = array(
+				'description' => __( 'Limit result set based on relationship between multiple taxonomies.' ),
+				'type'        => 'string',
+				'enum'        => array( 'AND', 'OR' ),
+			);
+		}
+
 		foreach ( $taxonomies as $taxonomy ) {
 			$base = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 530cc08646..c26f152664 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.4-alpha-46645';
+$wp_version = '5.4-alpha-46646';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.