diff --git a/docs/README.txt b/docs/README.txt
index 22cf9307795..3d634292980 100644
--- a/docs/README.txt
+++ b/docs/README.txt
@@ -40,3 +40,12 @@ The correspondence between .rst files and man pages is
 These .rst files are also included during HTML generation so they are also
 viewable online (as noted above) at e.g.
 `http://llvm.org/docs/CommandGuide/Foo.html`.
+
+Checking links
+==============
+
+The reachibility of external links in the documentation can be checked by
+running:
+
+    cd docs/
+    make -f Makefile.sphinx linkcheck