Index: bin/sync/sync.8
===================================================================
--- bin/sync/sync.8
+++ bin/sync/sync.8
@@ -29,7 +29,7 @@
 .\"	@(#)sync.8	8.1 (Berkeley) 5/31/93
 .\" $FreeBSD$
 .\"
-.Dd May 31, 1993
+.Dd September 14, 2019
 .Dt SYNC 8
 .Os
 .Sh NAME
@@ -37,6 +37,9 @@
 .Nd force completion of pending disk writes (flush cache)
 .Sh SYNOPSIS
 .Nm
+.Op Ar number
+.Nm
+.Op arg
 .Sh DESCRIPTION
 The
 .Nm
@@ -61,6 +64,29 @@
 utility utilizes the
 .Xr sync 2
 function call.
+.Pp
+If
+.Nm
+is given a single numeric argument, it will call the
+.Xr sync 2
+function call that number of times; if it is given a non-numeric
+argument, or the number is 0 or negative, then
+.Nm
+will call the
+.Xr sync 2
+function call once for each argument, and one additional time.
+.Sh EXAMPLES
+Call the
+.Xr sync 2
+function once:
+.Dl $ sync
+.Pp
+Call the
+.Xr sync 2
+function three times:
+.Dl $ sync 3
+or:
+.Dl $ sync sync sync
 .Sh SEE ALSO
 .Xr fsync 2 ,
 .Xr sync 2 ,
Index: bin/sync/sync.c
===================================================================
--- bin/sync/sync.c
+++ bin/sync/sync.c
@@ -47,6 +47,24 @@
 int
 main(int argc __unused, char *argv[] __unused)
 {
-	sync();
+	long sync_count;
+
+	if (argc == 1)
+		sync_count = 1;
+	else {
+		sync_count = strtol(argv[1], NULL, 0);
+		/*
+		 * If argv[1] isn't a valid number -- or
+		 * if it's 0, or negative -- then we simply use
+		 * the number of arguments, including argv[0],
+		 * to indicate how many times to sync.
+		 * This allows "sync 10" and "sync sync sync"
+		 * (as examples) to work as expected.
+		 */
+		if (sync_count <= 0)
+			sync_count = argc;
+	}
+	while (sync_count--)
+		sync();
 	exit(0);
 }