diff --git a/pep-0517.txt b/pep-0517.txt
index ea00b34c590..292bad3ab90 100644
--- a/pep-0517.txt
+++ b/pep-0517.txt
@@ -157,6 +157,13 @@ specified in PYTHONPATH). Although Python automatically adds the working
 directory to ``sys.path`` in some situations, code to resolve the backend should
 not be affected by this.
 
+In order to allow build backends to build themselves, it is possible to supply
+an additional location to search for build backends with the
+``build-backend-location`` option. If specified, this must be a path relative
+to the root of the source tree which will be added to ``sys.path`` while the
+build backend is imported. Build frontends must remove this location from the
+module search path before executing the build backend hooks.
+
 If the ``pyproject.toml`` file is absent, or the ``build-backend``
 key is missing, the source tree is not using this specification, and
 tools should fall back to running ``setup.py``.