diff --git a/tests/sys/fs/tmpfs/Makefile b/tests/sys/fs/tmpfs/Makefile
--- a/tests/sys/fs/tmpfs/Makefile
+++ b/tests/sys/fs/tmpfs/Makefile
@@ -7,6 +7,9 @@
 
 TESTSRC=		${SRCTOP}/contrib/netbsd-tests/fs/${FILESYSTEM}
 
+ATF_TESTS_SH+=		fsx_test
+TEST_METADATA.fsx_test+=	required_programs="fsx"
+
 # XXX: uses /dev/MAKEDEV to create pseudo /dev/{null,zero} character devices
 #NETBSD_ATF_TESTS_SH+=	devices_test
 NETBSD_ATF_TESTS_SH+=	create_test
diff --git a/tests/sys/fs/tmpfs/fsx_test.sh b/tests/sys/fs/tmpfs/fsx_test.sh
new file mode 100644
--- /dev/null
+++ b/tests/sys/fs/tmpfs/fsx_test.sh
@@ -0,0 +1,56 @@
+# Stress tests based on fsx
+
+# General stress test of all supported operations.  This test case uses a
+# random seed.  If it ever fails, find the seed in the test output, and create
+# a new test case using that fixed seed.
+atf_test_case stress
+stress_head()
+{
+	atf_set "descr" "General stress test based on all FSX operations"
+	atf_set "require.user" "root"
+}
+stress_body()
+{
+	test_mount
+
+	cat > ../fsx.toml << HERE
+flen = 1048576
+nomsyncafterwrite = true
+nosizechecks = false
+blockmode = false
+
+[opsize]
+max = 262144
+min = 0
+align = 1
+
+[weights]
+close_open = 1
+read = 5
+write = 5
+mapread = 5
+mapwrite = 5
+invalidate = 1
+truncate = 1
+fsync = 1
+fdatasync = 1
+posix_fallocate = 1
+punch_hole = 1
+sendfile = 1
+posix_fadvise = 1
+copy_file_range = 1
+HERE
+	fsx -f ../fsx.toml -N 1024 testfile
+	atf_check_equal 0 $?
+	rm ../fsx.toml
+
+	test_unmount
+}
+
+atf_init_test_cases()
+{
+	. $(atf_get_srcdir)/../h_funcs.subr
+	. $(atf_get_srcdir)/h_funcs.subr
+
+	atf_add_test_case stress
+}