diff --git a/ChangeLog b/ChangeLog
index 6f9e439..c8d9dd1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-03  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* config.guess (sun4*:SunOS:5.*:*): Return sparcv9-sun-solaris2.*
+	with 64-bit compiler.
+	(tadpole*:SunOS:5.*:*): Likewise.
+
 2019-01-03  Ben Elliston  <bje@gnu.org>
 
 	* testsuite/config-guess.data: Add a test for ARM Linux.
diff --git a/config.guess b/config.guess
index 0f9b29c..8e2a58b 100755
--- a/config.guess
+++ b/config.guess
@@ -2,7 +2,7 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2019 Free Software Foundation, Inc.
 
-timestamp='2019-01-01'
+timestamp='2019-01-03'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -385,7 +385,20 @@ case "$UNAME_MACHINE:$UNAME_SYSTEM:$UNAME_RELEASE:$UNAME_VERSION" in
 	echo sparc-hal-solaris2"`echo "$UNAME_RELEASE"|sed -e 's/[^.]*//'`"
 	exit ;;
     sun4*:SunOS:5.*:* | tadpole*:SunOS:5.*:*)
-	echo sparc-sun-solaris2"`echo "$UNAME_RELEASE" | sed -e 's/[^.]*//'`"
+	set_cc_for_build
+	SUN_ARCH=sparc
+	# 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 __sparcv9'; echo IS_64BIT_ARCH; echo '#endif') | \
+		(CCOPTS="" $CC_FOR_BUILD -E - 2>/dev/null) | \
+		grep IS_64BIT_ARCH >/dev/null
+	    then
+		SUN_ARCH=sparcv9
+	    fi
+	fi
+	echo "$SUN_ARCH"-sun-solaris2"`echo "$UNAME_RELEASE"|sed -e 's/[^.]*//'`"
 	exit ;;
     i86pc:AuroraUX:5.*:* | i86xen:AuroraUX:5.*:*)
 	echo i386-pc-auroraux"$UNAME_RELEASE"