diff --git a/doc/src/sgml/regress.sgml b/doc/src/sgml/regress.sgml
index 8f032c4e7a..58e144dde7 100644
--- a/doc/src/sgml/regress.sgml
+++ b/doc/src/sgml/regress.sgml
@@ -763,6 +763,25 @@ make check PROVE_TESTS='t/001_test1.pl t/003_test3.pl'
 </programlisting>
    </para>
 
+   <para>
+    Data directories are named according to the test filename, and will be
+    retained if a test fails.  If the environment variable
+    <varname>PG_TEST_NOCLEAN</varname> is set, data directories will be
+    retained regardless of test status.  For example, retaining the data
+    directory regardless of test results when running the
+    <application>pg_dump</application> tests:
+<programlisting>
+PG_TEST_NOCLEAN make -C src/bin/pg_dump check
+</programlisting>
+   </para>
+
+   <para>
+    Many operations in the test suites use a 180 second timeout, which on slow
+    hosts may lead to load-induced timeouts.  Setting the environment variable
+    <varname>PG_TEST_TIMEOUT_DEFAULT</varname> to a higher number will change
+    the default to avoid this.
+   </para>
+
    <para>
     The TAP tests require the Perl module <literal>IPC::Run</literal>.
     This module is available from CPAN or an operating system package.