Index: src/wp-includes/post.php
===================================================================
--- src/wp-includes/post.php	(revision 45565)
+++ src/wp-includes/post.php	(working copy)
@@ -2631,16 +2631,55 @@
  * Get default post mime types.
  *
  * @since 2.9.0
+ * @since 5.3.0 Added the 'Documents' mime types group.
  *
  * @return array List of post mime types.
  */
 function get_post_mime_types() {
+	$ext_types  = wp_get_ext_types();
+	$mime_types = wp_get_mime_types();
+
+	$doc_mime_types = '';
+
+	if ( isset( $ext_types['document'] ) ) {
+		$doc_mime_types = array();
+		foreach ( $ext_types['document'] as $extension ) {
+			foreach ( $mime_types as $exts => $mime ) {
+				if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
+					$doc_mime_types[] = $mime;
+					break;
+				}
+			}
+		}
+		$doc_mime_types = implode( ',', array_unique( $doc_mime_types ) );
+	}
+
 	$post_mime_types = array(   //	array( adj, noun )
-		'image' => array( __( 'Images' ), __( 'Manage Images' ), _n_noop( 'Image <span class="count">(%s)</span>', 'Images <span class="count">(%s)</span>' ) ),
-		'audio' => array( __( 'Audio' ), __( 'Manage Audio' ), _n_noop( 'Audio <span class="count">(%s)</span>', 'Audio <span class="count">(%s)</span>' ) ),
-		'video' => array( __( 'Video' ), __( 'Manage Video' ), _n_noop( 'Video <span class="count">(%s)</span>', 'Video <span class="count">(%s)</span>' ) ),
+		'image' => array(
+			__( 'Images' ),
+			__( 'Manage Images' ),
+			_n_noop( 'Image <span class="count">(%s)</span>', 'Images <span class="count">(%s)</span>' ),
+		),
+		'audio' => array(
+			__( 'Audio' ),
+			__( 'Manage Audio' ),
+			_n_noop( 'Audio <span class="count">(%s)</span>', 'Audio <span class="count">(%s)</span>' ),
+		),
+		'video' => array(
+			__( 'Video' ),
+			__( 'Manage Video' ),
+			_n_noop( 'Video <span class="count">(%s)</span>', 'Video <span class="count">(%s)</span>' ),
+		),
 	);
 
+	if ( $doc_mime_types ) {
+		$post_mime_types[ $doc_mime_types ] = array(
+			__( 'Documents' ),
+			__( 'Manage Documents' ),
+			_n_noop( 'Document <span class="count">(%s)</span>', 'Documents <span class="count">(%s)</span>' ),
+		);
+	}
+
 	/**
 	 * Filters the default list of post mime types.
 	 *