Index: bp-activity/bp-activity-actions.php
===================================================================
--- bp-activity/bp-activity-actions.php
+++ bp-activity/bp-activity-actions.php
@@ -645,3 +645,37 @@ function bp_activity_setup_akismet() {
 	// Instantiate Akismet for BuddyPress
 	$bp->activity->akismet = new BP_Akismet();
 }
+
+/**
+ * Deletes all associated activity comments and related meta entries for
+ * deleted activity items.
+ *
+ * @since BuddyPress (1.9)
+ *
+ * @param array $activity_ids The activity IDs that were deleted.
+ */
+function bp_activity_delete_activity_comments_and_meta( $activity_ids = array() ) {
+	global $wpdb;
+
+	$bp = buddypress();
+
+	$activity_ids                = wp_parse_id_list( $activity_ids );
+	$activity_ids_comma          = implode( ',', $activity_ids );
+	$activity_comments_where_sql = "WHERE type = 'activity_comment' AND item_id IN ({$activity_ids_comma})";
+
+	// Fetch the activity comment IDs for our deleted activity items
+	$activity_comment_ids = $wpdb->get_col( "SELECT id FROM {$bp->activity->table_name} {$activity_comments_where_sql}" );
+
+	// We have activity comments!
+	if ( ! empty( $activity_comment_ids ) ) {
+		// Delete activity comments
+		$wpdb->query( "DELETE FROM {$bp->activity->table_name} {$activity_comments_where_sql}" );
+
+		// Merge activity IDs with activity comment IDs
+		$activity_ids = array_merge( $activity_ids, $activity_comment_ids );
+	}
+
+	// Delete all activity meta entries for activity items and activity comments
+	BP_Activity_Activity::delete_activity_meta_entries( $activity_ids );
+}
+add_action( 'bp_activity_deleted_activities', 'bp_activity_delete_activity_comments_and_meta', 20 );
Index: bp-activity/bp-activity-classes.php
===================================================================
--- bp-activity/bp-activity-classes.php
+++ bp-activity/bp-activity-classes.php
@@ -456,13 +456,6 @@ class BP_Activity_Activity {
 		if ( !$wpdb->query( "DELETE FROM {$bp->activity->table_name} {$where_sql}" ) )
 			return false;
 
-		if ( $activity_ids ) {
-			BP_Activity_Activity::delete_activity_item_comments( $activity_ids );
-			BP_Activity_Activity::delete_activity_meta_entries( $activity_ids );
-
-			return $activity_ids;
-		}
-
 		return $activity_ids;
 	}
 
Index: tests/testcases/activity/functions.php
===================================================================
--- tests/testcases/activity/functions.php
+++ tests/testcases/activity/functions.php
@@ -34,4 +34,56 @@ class BP_Tests_Activity_Functions extends BP_UnitTestCase {
 		$this->assertEquals( bp_activity_thumbnail_content_images( $post_content ), '<img src="http://example.com/foo.jpg" width="40" height="40" alt="Thumbnail" class="align-left thumbnail" /> Awesome.' );
 	}
 
+	/**
+	 * @group delete
+	 */
+	public function test_delete_activity_and_meta() {
+		// create an activity update
+		$parent_activity = $this->factory->activity->create( array(
+			'type' => 'activity_update',
+		) );
+
+		// create some activity comments
+		$comment_one = $this->factory->activity->create( array(
+			'type'              => 'activity_comment',
+			'item_id'           => $parent_activity,
+			'secondary_item_id' => $parent_activity,
+		) );
+
+		$comment_two = $this->factory->activity->create( array(
+			'type'              => 'activity_comment',
+			'item_id'           => $parent_activity,
+			'secondary_item_id' => $parent_activity,
+		) );
+
+		// add some meta to the activity items
+		bp_activity_update_meta( $parent_activity, 'foo', 'bar' );
+		bp_activity_update_meta( $comment_one,     'foo', 'bar' );
+		bp_activity_update_meta( $comment_two,     'foo', 'bar' );
+
+		// now delete the parent activity item
+		// this should hopefully delete the associated comments and meta entries
+		bp_activity_delete( array(
+			'id' => $parent_activity
+		) );
+
+		// now fetch the deleted activity entries
+		$get = bp_activity_get( array(
+			'in'               => array( $parent_activity, $comment_one, $comment_two ),
+			'display_comments' => 'stream'
+		) );
+
+		// activities should equal zero
+		$this->assertEquals( 0, $get['total'] );
+
+		// now fetch activity meta for the deleted activity entries
+		$m1 = bp_activity_get_meta( $parent_activity );
+		$m2 = bp_activity_get_meta( $comment_one );
+		$m3 = bp_activity_get_meta( $comment_two );
+
+		// test if activity meta entries still exist
+		$this->assertEquals( false, $m1 );
+		$this->assertEquals( false, $m2 );
+		$this->assertEquals( false, $m3 );
+	}
 }