diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c3ae17aa3a6f..6c17ce4dd7d3 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-07-03  Richard Guenther  <rguenther@suse.de>
+
+	* doc/install.texi (CLooG): Clarify how CLooG needs to be
+	configured and that it needs to be built against ISL 0.10.
+
 2012-07-03  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.c (ix86_option_override_internal): Fix wrong
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 436f6567d539..b35d803b21e6 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -376,6 +376,10 @@ Necessary to build GCC with the Graphite loop optimizations.  It can be
 downloaded from @uref{ftp://gcc.gnu.org/pub/gcc/infrastructure/} as
 @file{cloog-0.17.0.tar.gz}.  The @option{--with-cloog} configure option should
 be used if CLooG is not installed in your default library search path.
+CLooG needs to be built against ISL 0.10, not its included copy of ISL
+which is too old.  Use @option{--with-isl=system} to direct CLooG to pick
+up an already installed ISL.  CLooG needs to be configured to use GMP
+internally, use @option{--with-bits=gmp} to direct it to do that.
 
 @end table