diff --git a/ChangeLog b/ChangeLog
index f360ba1..6d04e5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-07-18  Ben Elliston  <bje@gnu.org>
+
+	From Apostolos Syropoulos <asyropoulos@gmail.com>:
+	* config.guess (i86pc:SunOS:5.*:* | i86xen:SunOS:5.*:*): Use the
+	isainfo(1) command to guess what kind of system we have. Running
+	isainfo -b returns either "32" or "64".
+
 2018-07-18  Mikaël Urankar  <mikael.urankar@gmail.com>
 
 	* config.guess (arm*:FreeBSD:*:*): New.
diff --git a/config.guess b/config.guess
index 2c6634f..ba6af63 100755
--- a/config.guess
+++ b/config.guess
@@ -392,20 +392,15 @@ case "$UNAME_MACHINE:$UNAME_SYSTEM:$UNAME_RELEASE:$UNAME_VERSION" in
 	echo i386-pc-auroraux"$UNAME_RELEASE"
 	exit ;;
     i86pc:SunOS:5.*:* | i86xen:SunOS:5.*:*)
-	set_cc_for_build
-	SUN_ARCH=i386
-	# If there is a compiler, see if it is configured for 64-bit objects.
-	# Note that the Sun cc does not turn __LP64__ into 1 like gcc does.
-	# This test works for both compilers.
-	if [ "$CC_FOR_BUILD" != no_compiler_found ]; then
-	    if (echo '#ifdef __amd64'; echo IS_64BIT_ARCH; echo '#endif') | \
-		(CCOPTS="" $CC_FOR_BUILD -E - 2>/dev/null) | \
-		grep IS_64BIT_ARCH >/dev/null
-	    then
-		SUN_ARCH=x86_64
-	    fi
-	fi
-	echo "$SUN_ARCH"-pc-solaris2"`echo "$UNAME_RELEASE"|sed -e 's/[^.]*//'`"
+	UNAME_REL="`echo "$UNAME_RELEASE" | sed -e 's/[^.]*//'`"
+	case `isainfo -b` in
+	    32)
+		echo i386-pc-solaris2"$UNAME_REL"
+		;;
+	    64)
+		echo x86_64-pc-solaris2"$UNAME_REL"
+		;;
+	esac
 	exit ;;
     sun4*:SunOS:6*:*)
 	# According to config.sub, this is the proper way to canonicalize