diff --git a/bin/cp/cp.1 b/bin/cp/cp.1
--- a/bin/cp/cp.1
+++ b/bin/cp/cp.1
@@ -29,7 +29,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 28, 2024
+.Dd July 1, 2025
 .Dt CP 1
 .Os
 .Sh NAME
@@ -42,7 +42,7 @@
 .Op Fl H | Fl L | Fl P
 .Oc
 .Op Fl f | i | n
-.Op Fl alNpsvx
+.Op Fl alNpSsvx
 .Ar source_file target_file
 .Nm
 .Oo
@@ -50,15 +50,15 @@
 .Op Fl H | Fl L | Fl P
 .Oc
 .Op Fl f | i | n
-.Op Fl alNpsvx
+.Op Fl alNpSsvx
 .Ar source_file ... target_directory
 .Nm
 .Op Fl f | i | n
-.Op Fl alNPpsvx
+.Op Fl alNPpSsvx
 .Ar source_file target_file
 .Nm
 .Op Fl f | i | n
-.Op Fl alNPpsvx
+.Op Fl alNPpSsvx
 .Ar source_file ... target_directory
 .Sh DESCRIPTION
 In the first synopsis form, the
@@ -137,9 +137,7 @@
 .Fl n
 options.)
 .It Fl i
-Cause
-.Nm
-to write a prompt to the standard error output before copying a file
+Write a prompt to the standard error output before copying a file
 that would overwrite an existing file.
 If the response from the standard input begins with the character
 .Sq Li y
@@ -169,9 +167,7 @@
 .Fl i
 options.)
 .It Fl p
-Cause
-.Nm
-to preserve the following attributes of each source
+Preserve the following attributes of each source
 file in the copy: modification time, access time,
 file flags, file mode, ACL, user ID, and group ID, as allowed by permissions.
 .Pp
@@ -188,14 +184,25 @@
 and either the user ID or group ID cannot be preserved, neither
 the set-user-ID nor set-group-ID bits are preserved in the copy's
 permissions.
+.It Fl S
+Visit and traverse sources in (non-localized) lexicographical order.
+Normally,
+.Nm
+visits the sources in the order they were listed on the command line,
+and if recursing, traverses their contents in whichever order they
+were returned in by the kernel, which may be the order in which they
+were created, lexicographical order, or something else entirely.
+With
+.Fl S ,
+the sources are both visited and traversed in lexicographical order.
+This is mostly useful for testing.
 .It Fl s
 Create symbolic links to regular files in a hierarchy instead of copying.
 .It Fl v
-Cause
-.Nm
-to be verbose, showing files as they are copied.
+Be verbose, showing both the source and destination path of each file
+as is copied.
 .It Fl x
-File system mount points are not traversed.
+Do not traverse file system mount points.
 .El
 .Pp
 For each destination file that already exists, its contents are
diff --git a/bin/cp/cp.c b/bin/cp/cp.c
--- a/bin/cp/cp.c
+++ b/bin/cp/cp.c
@@ -69,8 +69,8 @@
 
 #define END(buf) (buf + sizeof(buf))
 PATH_T to = { .dir = -1, .end = to.path };
-int Nflag, fflag, iflag, lflag, nflag, pflag, sflag, vflag;
-static int Hflag, Lflag, Pflag, Rflag, rflag;
+bool Nflag, fflag, iflag, lflag, nflag, pflag, sflag, vflag;
+static bool Hflag, Lflag, Pflag, Rflag, rflag, Sflag;
 volatile sig_atomic_t info;
 
 enum op { FILE_TO_FILE, FILE_TO_DIR, DIR_TO_DNE };
@@ -88,59 +88,62 @@
 	bool have_trailing_slash = false;
 
 	fts_options = FTS_NOCHDIR | FTS_PHYSICAL;
-	while ((ch = getopt(argc, argv, "HLPRafilNnprsvx")) != -1)
+	while ((ch = getopt(argc, argv, "HLPRafilNnprSsvx")) != -1)
 		switch (ch) {
 		case 'H':
-			Hflag = 1;
-			Lflag = Pflag = 0;
+			Hflag = true;
+			Lflag = Pflag = false;
 			break;
 		case 'L':
-			Lflag = 1;
-			Hflag = Pflag = 0;
+			Lflag = true;
+			Hflag = Pflag = false;
 			break;
 		case 'P':
-			Pflag = 1;
-			Hflag = Lflag = 0;
+			Pflag = true;
+			Hflag = Lflag = false;
 			break;
 		case 'R':
-			Rflag = 1;
+			Rflag = true;
 			break;
 		case 'a':
-			pflag = 1;
-			Rflag = 1;
-			Pflag = 1;
-			Hflag = Lflag = 0;
+			pflag = true;
+			Rflag = true;
+			Pflag = true;
+			Hflag = Lflag = false;
 			break;
 		case 'f':
-			fflag = 1;
-			iflag = nflag = 0;
+			fflag = true;
+			iflag = nflag = false;
 			break;
 		case 'i':
-			iflag = 1;
-			fflag = nflag = 0;
+			iflag = true;
+			fflag = nflag = false;
 			break;
 		case 'l':
-			lflag = 1;
+			lflag = true;
 			break;
 		case 'N':
-			Nflag = 1;
+			Nflag = true;
 			break;
 		case 'n':
-			nflag = 1;
-			fflag = iflag = 0;
+			nflag = true;
+			fflag = iflag = false;
 			break;
 		case 'p':
-			pflag = 1;
+			pflag = true;
 			break;
 		case 'r':
-			rflag = Lflag = 1;
-			Hflag = Pflag = 0;
+			rflag = Lflag = true;
+			Hflag = Pflag = false;
+			break;
+		case 'S':
+			Sflag = true;
 			break;
 		case 's':
-			sflag = 1;
+			sflag = true;
 			break;
 		case 'v':
-			vflag = 1;
+			vflag = true;
 			break;
 		case 'x':
 			fts_options |= FTS_XDEV;
@@ -159,7 +162,7 @@
 	if (lflag && sflag)
 		errx(1, "the -l and -s options may not be specified together");
 	if (rflag)
-		Rflag = 1;
+		Rflag = true;
 	if (Rflag) {
 		if (Hflag)
 			fts_options |= FTS_COMFOLLOW;
@@ -262,6 +265,12 @@
 	    &to_stat)));
 }
 
+static int
+ftscmp(const FTSENT * const *a, const FTSENT * const *b)
+{
+	return (strcmp((*a)->fts_name, (*b)->fts_name));
+}
+
 static int
 copy(char *argv[], enum op type, int fts_options, struct stat *root_stat)
 {
@@ -305,7 +314,7 @@
 	}
 
 	level = FTS_ROOTLEVEL;
-	if ((ftsp = fts_open(argv, fts_options, NULL)) == NULL)
+	if ((ftsp = fts_open(argv, fts_options, Sflag ? ftscmp : NULL)) == NULL)
 		err(1, "fts_open");
 	for (badcp = rval = 0;
 	     (curr = fts_read(ftsp)) != NULL;
diff --git a/bin/cp/extern.h b/bin/cp/extern.h
--- a/bin/cp/extern.h
+++ b/bin/cp/extern.h
@@ -37,7 +37,7 @@
 } PATH_T;
 
 extern PATH_T to;
-extern int Nflag, fflag, iflag, lflag, nflag, pflag, sflag, vflag;
+extern bool Nflag, fflag, iflag, lflag, nflag, pflag, sflag, vflag;
 extern volatile sig_atomic_t info;
 
 __BEGIN_DECLS
diff --git a/bin/cp/tests/cp_test.sh b/bin/cp/tests/cp_test.sh
--- a/bin/cp/tests/cp_test.sh
+++ b/bin/cp/tests/cp_test.sh
@@ -649,7 +649,7 @@
 	atf_check \
 	    -s exit:1 \
 	    -e match:"^cp: src/b: Permission denied" \
-	    cp -R src dst
+	    cp -RS src dst
 	atf_check test -d dst/a
 	atf_check \
 	    -o inline:"a\n" \
@@ -676,7 +676,7 @@
 	atf_check \
 	    -s exit:1 \
 	    -e match:"^cp: src/b: Permission denied" \
-	    cp -R src dst
+	    cp -RS src dst
 	atf_check test -d dst
 	atf_check \
 	    -o inline:"a\n" \
diff --git a/bin/cp/utils.c b/bin/cp/utils.c
--- a/bin/cp/utils.c
+++ b/bin/cp/utils.c
@@ -105,7 +105,7 @@
 	ssize_t wcount;
 	off_t wtotal;
 	int ch, checkch, from_fd, rval, to_fd;
-	int use_copy_file_range = 1;
+	bool use_copy_file_range = true;
 
 	fs = entp->fts_statp;
 	from_fd = to_fd = -1;
@@ -210,7 +210,7 @@
 			    to_fd, NULL, SSIZE_MAX, 0);
 			if (wcount < 0 && errno == EINVAL) {
 				/* probably a non-seekable descriptor */
-				use_copy_file_range = 0;
+				use_copy_file_range = false;
 			}
 		}
 		if (!use_copy_file_range) {