diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 6bac0c3..0384c1c 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -13652,6 +13652,18 @@ appear literally in the updated @file{configure.ac}.
 @auindex{ALIAS}
 Used if the @var{old-name} is to be replaced by a call to @var{new-macro}
 with the same parameters.  This happens for example if the macro was renamed.
+A typical use of @code{AU_ALIAS} looks like this:
+
address@hidden
+AC_DEFUN([AC_CHECK_FOO], [...])
+AU_ALIAS([AC_HAVE_FOO], [AC_CHECK_FOO])
address@hidden example
+
+where `...' is a sensible definition of the @code{AC_CHECK_FOO} macro.
+This announces @code{AC_HAVE_FOO} as an old macro name that should
+expand to the contents of the @code{AC_CHECK_FOO} macro when autoconf
+is run, and should replace invocations of @code{AC_HAVE_FOO} with
+invocations of @code{AC_CHECK_FOO} when autoupdate is run.
 @end defmac
 
 @node Coding Style