diff --git a/etc/mtree/BSD.tests.dist b/etc/mtree/BSD.tests.dist
index 8b985f3b468..8a3b097c416 100644
--- a/etc/mtree/BSD.tests.dist
+++ b/etc/mtree/BSD.tests.dist
@@ -1087,6 +1087,8 @@
         ..
         lockf
         ..
+        lorder
+        ..
         m4
         ..
         mkimg
diff --git a/usr.bin/lorder/Makefile b/usr.bin/lorder/Makefile
index a94860b51c6..6b3fa2c829d 100644
--- a/usr.bin/lorder/Makefile
+++ b/usr.bin/lorder/Makefile
@@ -1,6 +1,10 @@
 #	@(#)Makefile	8.1 (Berkeley) 6/6/93
+.include <src.opts.mk>
 
 SCRIPTS=lorder.sh
 MAN=	lorder.1
 
+HAS_TESTS=
+SUBDIR.${MK_TESTS}=	tests
+
 .include <bsd.prog.mk>
diff --git a/usr.bin/lorder/lorder.1 b/usr.bin/lorder/lorder.1
index e268f81d725..478b7f493e0 100644
--- a/usr.bin/lorder/lorder.1
+++ b/usr.bin/lorder/lorder.1
@@ -27,17 +27,12 @@
 .\"
 .\"     @(#)lorder.1	8.2 (Berkeley) 4/28/95
 .\"
-.Dd March 21, 2023
+.Dd February 27, 2024
 .Dt LORDER 1
 .Os
 .Sh NAME
 .Nm lorder
 .Nd list dependencies for object files
-.Sh DEPRECATION NOTICE
-.Nm
-is obsolete and may not be present in
-.Fx 14
-and later.
 .Sh SYNOPSIS
 .Nm
 .Ar
@@ -46,13 +41,10 @@ The
 .Nm
 utility uses
 .Xr nm 1
-to determine interdependencies in the list of object files
-and library archives
-specified on the command line.
-The
-.Nm
-utility outputs a list of file names where the first file contains a symbol
-which is defined by the second file.
+to determine interdependencies between object files and library
+archives listed on its command line.
+It then outputs a list of pairs of file names such that the first file
+in each pair references at least one symbol defined by the second.
 .Pp
 The output is normally used with
 .Xr tsort 1
@@ -60,18 +52,16 @@ when a library is created to determine the optimum ordering of the
 object modules so that all references may be resolved in a single
 pass of the loader.
 .Pp
-When linking static binaries,
+Similarly, when linking static binaries,
 .Nm
 and
 .Xr tsort 1
-can be used to properly order library archives automatically.
+can be used to sort libraries in order of dependency.
 .Pp
-The use of
-.Nm
-is not required by contemporary linkers, and
-.Nm
-may be removed from a future version of
-.Fx .
+While contemporary linkers no longer require the use of
+.Nm ,
+it is provided for the benefit of legacy code bases and build
+systems which still insist on it.
 .Sh ENVIRONMENT
 .Bl -tag -width indent
 .It Ev NM
@@ -99,3 +89,8 @@ A
 .Nm
 utility appeared in
 .At v7 .
+.Sh CAVEATS
+The
+.Nm
+utility will not work properly if given file names with spaces or
+newlines in them.
diff --git a/usr.bin/lorder/lorder.sh b/usr.bin/lorder/lorder.sh
index 640e128b0cb..c0a7dbbd43e 100644
--- a/usr.bin/lorder/lorder.sh
+++ b/usr.bin/lorder/lorder.sh
@@ -33,35 +33,50 @@
 #
 #
 
-# only one argument is a special case, just output the name twice
-case $# in
-	0)
-		echo "usage: lorder file ...";
-		exit ;;
-	1)
-		echo $1 $1;
-		exit ;;
-esac
+export LC_CTYPE=C
+export LC_COLLATE=C
+set -e
 
-# temporary files
+usage() {
+	echo "usage: lorder file ..." >&2
+	exit 1
+}
+
+while getopts "" opt ; do
+	case $opt in
+	*)
+		usage
+		;;
+	esac
+done
+shift $(($OPTIND - 1))
+if [ $# -eq 0 ] ; then
+	usage
+fi
+
+#
+# Create temporary files.
+#
+N=$(mktemp -t _nm_)
 R=$(mktemp -t _reference_)
 S=$(mktemp -t _symbol_)
+T=$(mktemp -t _temp_)
 NM=${NM:-nm}
 
-# remove temporary files on HUP, INT, QUIT, PIPE, TERM
-trap "rm -f $R $S $T; exit 1" 1 2 3 13 15
-
-# make sure all the files get into the output
-for i in $*; do
-	echo $i $i
-done
-
-# if the line has " [RTDW] " it's a globally defined symbol, put it
-# into the symbol file.
 #
-# if the line has " U " it's a globally undefined symbol, put it into
-# the reference file.
-${NM} ${NMFLAGS} -go $* | sed "
+# Remove temporary files on termination.
+#
+trap "rm -f $N $R $S $T" EXIT 1 2 3 13 15
+
+#
+# A line matching " [RTDW] " indicates that the input defines a symbol
+# with external linkage; put it in the symbol file.
+#
+# A line matching " U " indicates that the input references an
+# undefined symbol; put it in the reference file.
+#
+${NM} ${NMFLAGS} -go "$@" >$N
+sed -e "
 	/ [RTDW] / {
 		s/:.* [RTDW] / /
 		w $S
@@ -72,21 +87,28 @@ ${NM} ${NMFLAGS} -go $* | sed "
 		w $R
 	}
 	d
-"
+" <$N
 
-export LC_ALL=C
-# eliminate references that can be resolved by the same library.
-if [ $(expr "$*" : '.*\.a[[:>:]]') -ne 0 ]; then
-	sort -u -o $S $S
-	sort -u -o $R $R
-	T=$(mktemp -t _temp_)
-	comm -23 $R $S >$T
-	mv $T $R
-fi
+#
+# Elide entries representing a reference to a symbol from within the
+# library that defines it.
+#
+sort -u -o $S $S
+sort -u -o $R $R
+comm -23 $R $S >$T
+mv $T $R
 
-# sort references and symbols on the second field (the symbol),
-# join on that field, and print out the file names.
+#
+# Make sure that all inputs get into the output.
+#
+for i ; do
+	echo "$i" "$i"
+done
+
+#
+# Sort references and symbols on the second field (the symbol), join
+# on that field, and print out the file names.
+#
 sort -k 2 -o $R $R
 sort -k 2 -o $S $S
-join -j 2 -o 1.1 2.1 $R $S
-rm -f $R $S
+join -j 2 -o 1.1 -o 2.1 $R $S
diff --git a/usr.bin/lorder/tests/Makefile b/usr.bin/lorder/tests/Makefile
new file mode 100644
index 00000000000..21207f413a8
--- /dev/null
+++ b/usr.bin/lorder/tests/Makefile
@@ -0,0 +1,4 @@
+PACKAGE=	tests
+ATF_TESTS_SH=	lorder_test
+
+.include <bsd.test.mk>
diff --git a/usr.bin/lorder/tests/lorder_test.sh b/usr.bin/lorder/tests/lorder_test.sh
new file mode 100644
index 00000000000..a4276b2dcfe
--- /dev/null
+++ b/usr.bin/lorder/tests/lorder_test.sh
@@ -0,0 +1,111 @@
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+
+atf_test_case noargs
+noargs_head() {
+	atf_set descr "No arguments"
+}
+noargs_body() {
+	atf_check -s exit:1 -e match:"^usage:" \
+		  lorder
+}
+
+atf_test_case onearg
+onearg_head() {
+	atf_set descr "One argument"
+}
+onearg_body() {
+	echo "void a(void) { }" >a.c
+	cc -o a.o -c a.c
+	echo "a.o a.o" >output
+	atf_check -o file:output \
+		  lorder *.o
+}
+
+atf_test_case dashdash
+dashdash_head() {
+	atf_set descr "One argument"
+}
+dashdash_body() {
+	echo "void a(void) { }" >a.c
+	cc -o a.o -c a.c
+	echo "a.o a.o" >output
+	atf_check -o file:output \
+		  lorder -- *.o
+}
+
+atf_test_case nonexistent
+nonexistent_head() {
+	atf_set descr "Nonexistent file"
+}
+nonexistent_body() {
+	atf_check -s not-exit:0 -e match:"No such file" -o empty \
+		  lorder nonexistent.o
+}
+
+atf_test_case invalid
+invalid_head() {
+	atf_set descr "Invalid file"
+}
+invalid_body() {
+	echo "not an object file" >invalid.o
+	atf_check -s not-exit:0 -e match:"not recognized" -o empty \
+		  lorder invalid.o
+}
+
+atf_test_case objects
+objects_head() {
+	atf_set descr "Order objects"
+}
+objects_body() {
+	echo "void a(void) { }" >a.c
+	echo "void a(void); void b(void) { a(); }" >b.c
+	echo "void b(void); void c(void) { b(); }" >c.c
+	for n in a b c ; do
+		cc -o $n.o -c $n.c
+		echo "$n.o $n.o"
+	done >output
+	echo "b.o a.o" >>output
+	echo "c.o b.o" >>output
+	atf_check -o file:output \
+		  lorder *.o
+}
+
+atf_test_case archives
+archives_head() {
+	atf_set descr "Order archives"
+}
+archives_body() {
+	echo "void a(void) { }" >a.c
+	echo "void a(void); void b(void) { a(); }" >b.c
+	echo "void b(void); void c(void) { b(); }" >c.c
+	echo "void e(void); void d(void) { e(); }" >d.c
+	echo "void d(void); void e(void) { d(); }" >e.c
+	for n in a b c d e ; do
+		cc -o $n.o -c $n.c
+	done
+	for n in a b c ; do
+		ar -crs $n.a $n.o
+		echo "$n.a $n.a"
+	done >output
+	ar -crs z.a d.o e.o
+	echo "z.a z.a" >>output
+	echo "b.a a.a" >>output
+	echo "c.a b.a" >>output
+	atf_check -o file:output \
+		  lorder *.a
+}
+
+atf_init_test_cases()
+{
+	atf_add_test_case noargs
+	atf_add_test_case onearg
+	atf_add_test_case dashdash
+	atf_add_test_case nonexistent
+	atf_add_test_case invalid
+	atf_add_test_case objects
+	atf_add_test_case archives
+}