diff --git a/tools/Makefile b/tools/Makefile
index f5265331b5e3..50403a121b04 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.215 2023/11/30 06:29:33 rin Exp $
+#	$NetBSD: Makefile,v 1.216 2024/02/23 05:34:41 mrg Exp $
 
 .include <bsd.own.mk>
 .include <bsd.endian.mk>
@@ -31,6 +31,9 @@ TOOLCHAIN_BITS+= gmake .WAIT
 TOOLCHAIN_BITS+= gmp .WAIT
 TOOLCHAIN_BITS+= mpfr .WAIT
 TOOLCHAIN_BITS+= mpc .WAIT
+.  if (defined(HAVE_GCC) && ${HAVE_GCC} >= 12)
+TOOLCHAIN_BITS+= isl .WAIT
+.  endif
 . endif
 
 TOOLCHAIN_BITS+= binutils .WAIT
diff --git a/tools/isl/Makefile b/tools/isl/Makefile
new file mode 100644
index 000000000000..7b86e1f546a1
--- /dev/null
+++ b/tools/isl/Makefile
@@ -0,0 +1,16 @@
+#	$NetBSD: Makefile,v 1.1 2024/02/23 05:34:41 mrg Exp $
+
+GNUHOSTDIST=	${.CURDIR}/../../external/mit/isl/dist
+
+CONFIGURE_ARGS+=	--with-gmp-prefix=${TOOLDIR:Q} \
+			--disable-shared
+
+.include "${.CURDIR}/../Makefile.gmakehost"
+
+CONFIGURE_ENV+= MAKE=${TOOL_GMAKE}
+
+# XXX this gets lost some how.  Not portable.
+HOST_CXXFLAGS+=	-std=gnu++17
+
+# Force avoiding possibly non-executable install-sh.
+#CONFIGURE_ENV+= ac_cv_path_mkdir="${TOOLDIR}/bin/${MACHINE_GNU_PLATFORM}-install -d"