Index: src/wp-includes/meta.php
===================================================================
--- src/wp-includes/meta.php	(revision 37996)
+++ src/wp-includes/meta.php	(working copy)
@@ -1161,6 +1161,16 @@
 		return new WP_Error( 'invalid_meta_key', __( 'Invalid meta key' ) );
 	}
 
+	$args = $wp_meta_keys[ $object_type ][ $object_subtype ][ $meta_key ];
+
+	if ( isset( $args['sanitize_callback'] ) && is_callable( $args['sanitize_callback'] ) ) {
+		remove_filter( "sanitize_{$object_type}_{$object_subtype}_meta_{$meta_key}", $args['sanitize_callback'] );
+	}
+
+	if ( isset( $args['auth_callback'] ) && is_callable( $args['auth_callback'] ) ) {
+		remove_filter( "auth_{$object_type}_{$object_subtype}_meta_{$meta_key}", $args['auth_callback'] );
+	}
+
 	unset( $wp_meta_keys[ $object_type ][ $object_subtype ][ $meta_key ] );
 
 	// Do some clean up
Index: tests/phpunit/tests/meta/registerMeta.php
===================================================================
--- tests/phpunit/tests/meta/registerMeta.php	(revision 37995)
+++ tests/phpunit/tests/meta/registerMeta.php	(working copy)
@@ -32,6 +32,10 @@
 		return $meta_key . ' new sanitized';
 	}
 
+	public function _new_auth_meta_cb( $allowed, $meta_key, $post_id, $user_id, $cap, $caps ) {
+		return $allowed;
+	}
+
 	public function test_register_meta_with_valid_object_type_and_object_subtype_returns_true() {
 		$result = register_meta( 'post', 'flight_number', array( 'object_subtype' => 'post' ) );
 		unregister_meta_key( 'post', 'post', 'flight_number' );
@@ -200,9 +204,6 @@
 		$result = register_meta( 'post', 'flight_number', array( 'object_subtype' => 'post', 'sanitize_callback' => array( $this, '_new_sanitize_meta_cb' ) ) );
 		unregister_meta_key( 'post', 'post', 'flight_number' );
 
-		remove_filter( 'sanitize_post_post_meta_flight_number', array( $this, '_new_sanitize_meta_cb') );
-		remove_filter( 'auth_post_post_meta_flight_number', '__return_true');
-
 		$this->assertTrue( $result );
 	}
 
@@ -212,12 +213,27 @@
 
 		unregister_meta_key( 'post', 'post', 'new_sanitized_key' );
 
-		remove_filter( 'sanitize_post_post_meta_new_sanitized_key', array( $this, '_new_sanitize_meta_cb') );
-		remove_filter( 'auth_post_post_meta_new_sanitized_key', '__return_true');
-
 		$this->assertEquals( 'new_sanitized_key new sanitized', $meta );
 	}
 
+	public function test_register_meta_unregistered_meta_key_removes_sanitize_filter() {
+		register_meta( 'post', 'new_sanitized_key', array( 'object_subtype' => 'post', 'sanitize_callback' => array( $this, '_new_sanitize_meta_cb' ) ) );
+		unregister_meta_key( 'post', 'post', 'new_sanitized_key' );
+
+		$has_filter = has_filter( 'sanitize_post_post_meta_new_sanitized_key', array( $this, '_new_sanitize_meta_cb' ) );
+
+		$this->assertFalse( $has_filter );
+	}
+
+	public function test_register_meta_unregistered_meta_key_removes_auth_filter() {
+		register_meta( 'post', 'new_auth_key', array( 'object_subtype' => 'post', 'auth_callback' => array( $this, '_new_auth_meta_cb' ) ) );
+		unregister_meta_key( 'post', 'post', 'new_auth_key' );
+
+		$has_filter = has_filter( 'auth_post_post_meta_new_auth_key', array( $this, '_new_auth_meta_cb' ) );
+
+		$this->assertFalse( $has_filter );
+	}
+
 	public function test_unregister_meta_key_clears_key_from_wp_meta_keys() {
 		global $wp_meta_keys;
 		register_meta( 'post', 'registered_key', array( 'object_subtype' => 'post' ) );