diff --git a/docs/releases/1.1.rst b/docs/releases/1.1.rst
index cb4e19ae69..38a79ad52a 100644
--- a/docs/releases/1.1.rst
+++ b/docs/releases/1.1.rst
@@ -21,6 +21,11 @@ Usually, an operation that retrieves a queryset of pages (such as ``homepage.get
 Previously, this was implemented in :mod:`~wagtail.wagtailsearch` but now has
 been moved into a separate module: :mod:`wagtail.contrib.wagtailsearchpromotions`
 
+Atomic rebuilding of Elasticsearch indexes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Elasticsearch search backend now accepts an experimental ``ATOMIC_REBUILD`` flag which ensures that the existing search index continues to be available while the ``update_index`` task is running. See :ref:`wagtailsearch_backends_atomic_rebuild`.
+
 Minor features
 ~~~~~~~~~~~~~~
 
diff --git a/docs/topics/search/backends.rst b/docs/topics/search/backends.rst
index 0214d2e21a..319f4b2a93 100644
--- a/docs/topics/search/backends.rst
+++ b/docs/topics/search/backends.rst
@@ -41,6 +41,8 @@ The ``AUTO_UPDATE`` setting allows you to disable this on a per-index basis:
 If you have disabled auto update, you must run the :ref:`update_index` command on a regular basis to keep the index in sync with the database.
 
 
+.. _wagtailsearch_backends_atomic_rebuild:
+
 ``ATOMIC_REBUILD``
 ==================