diff --git a/usr.bin/procstat/Makefile b/usr.bin/procstat/Makefile
index 1744fe083214..211ce1a1431b 100644
--- a/usr.bin/procstat/Makefile
+++ b/usr.bin/procstat/Makefile
@@ -8,6 +8,7 @@ SRCS=	procstat.c		\
 	procstat_basic.c	\
 	procstat_bin.c		\
 	procstat_cred.c		\
+	procstat_cs.c		\
 	procstat_files.c	\
 	procstat_kstack.c	\
 	procstat_rlimit.c	\
diff --git a/usr.bin/procstat/procstat.1 b/usr.bin/procstat/procstat.1
index f33c746bc736..5cc7cc8785cc 100644
--- a/usr.bin/procstat/procstat.1
+++ b/usr.bin/procstat/procstat.1
@@ -35,7 +35,7 @@
 .Nm
 .Op Fl CHhn
 .Op Fl w Ar interval
-.Op Fl b | c | e | f | i | j | k | l | r | s | t | v | x
+.Op Fl b | c | e | f | i | j | k | l | r | s | S | t | v | x
 .Op Fl a | Ar pid | Ar core ...
 .Sh DESCRIPTION
 The
@@ -75,6 +75,8 @@ Display resource limits for the process.
 Display resource usage information for the process.
 .It Fl s
 Display security credential information for the process.
+.It Fl S
+Display the cpuset information for the thread.
 .It Fl t
 Display thread information for the process.
 .It Fl v
@@ -108,9 +110,16 @@ flag may be used to request per-thread statistics rather than per-process
 statistics for some options.
 For those options, the second field in the table will list the thread ID
 to which the row of information corresponds.
+The
+.Fl H
+flag is implied for the
+.Fl S
+mode.
 .Pp
-Some information, such as VM and file descriptor information, is available
+Information for VM, file descriptor, and cpuset options is available
 only to the owner of a process or the superuser.
+A cpuset value displayed as -1 means that the information is either invalid
+or not available.
 .Ss Binary Information
 Display the process ID, command, and path to the process binary:
 .Pp
diff --git a/usr.bin/procstat/procstat.c b/usr.bin/procstat/procstat.c
index de0237f387ce..0be90c334066 100644
--- a/usr.bin/procstat/procstat.c
+++ b/usr.bin/procstat/procstat.c
@@ -40,7 +40,7 @@
 #include "procstat.h"
 
 static int aflag, bflag, cflag, eflag, fflag, iflag, jflag, kflag, lflag, rflag;
-static int sflag, tflag, vflag, xflag;
+static int sflag, tflag, vflag, xflag, Sflag;;
 int	hflag, nflag, Cflag, Hflag;
 
 static void
@@ -50,7 +50,7 @@ usage(void)
 	fprintf(stderr, "usage: procstat [-CHhn] [-M core] [-N system] "
 	    "[-w interval] \n");
 	fprintf(stderr, "                [-b | -c | -e | -f | -i | -j | -k | "
-	    "-l | -r | -s | -t | -v | -x]\n");
+	    "-l | -r | -s | -S | -t | -v | -x]\n");
 	fprintf(stderr, "                [-a | pid | core ...]\n");
 	exit(EX_USAGE);
 }
@@ -85,6 +85,8 @@ procstat(struct procstat *prstat, struct kinfo_proc *kipp)
 		procstat_vm(prstat, kipp);
 	else if (xflag)
 		procstat_auxv(prstat, kipp);
+	else if (Sflag)
+		procstat_cs(prstat, kipp);
 	else
 		procstat_basic(kipp);
 }
@@ -128,7 +130,7 @@ main(int argc, char *argv[])
 
 	interval = 0;
 	memf = nlistf = NULL;
-	while ((ch = getopt(argc, argv, "CHN:M:abcefijklhrstvw:x")) != -1) {
+	while ((ch = getopt(argc, argv, "CHN:M:abcefijklhrsStvw:x")) != -1) {
 		switch (ch) {
 		case 'C':
 			Cflag++;
@@ -144,6 +146,9 @@ main(int argc, char *argv[])
 		case 'N':
 			nlistf = optarg;
 			break;
+		case 'S':
+			Sflag++;
+			break;
 		case 'a':
 			aflag++;
 			break;
@@ -228,7 +233,7 @@ main(int argc, char *argv[])
 
 	/* We require that either 0 or 1 mode flags be set. */
 	tmp = bflag + cflag + eflag + fflag + iflag + jflag + (kflag ? 1 : 0) +
-	    lflag + rflag + sflag + tflag + vflag + xflag;
+	    lflag + rflag + sflag + tflag + vflag + xflag + Sflag;
 	if (!(tmp == 0 || tmp == 1))
 		usage();
 
diff --git a/usr.bin/procstat/procstat.h b/usr.bin/procstat/procstat.h
index 98282b3ac1e0..50795219111f 100644
--- a/usr.bin/procstat/procstat.h
+++ b/usr.bin/procstat/procstat.h
@@ -39,6 +39,7 @@ void	procstat_auxv(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_basic(struct kinfo_proc *kipp);
 void	procstat_bin(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_cred(struct procstat *prstat, struct kinfo_proc *kipp);
+void	procstat_cs(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_env(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_files(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_kstack(struct procstat *prstat, struct kinfo_proc *kipp,
diff --git a/usr.bin/procstat/procstat_cs.c b/usr.bin/procstat/procstat_cs.c
new file mode 100644
index 000000000000..8ccf1ea82227
--- /dev/null
+++ b/usr.bin/procstat/procstat_cs.c
@@ -0,0 +1,108 @@
+/*-
+ * Copyright (c) 2007 Robert N. M. Watson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/cpuset.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+
+#include <err.h>
+#include <errno.h>
+#include <libprocstat.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "procstat.h"
+
+void
+procstat_cs(struct procstat *procstat, struct kinfo_proc *kipp)
+{
+	cpusetid_t cs;
+	cpuset_t mask;
+	struct kinfo_proc *kip;
+	unsigned int count, i;
+	int once, twice, lastcpu, cpu;
+
+	if (!hflag)
+		printf("%5s %6s %-16s %-16s %2s %4s %-7s\n", "PID",
+		    "TID", "COMM", "TDNAME", "CPU", "CSID", "CPU MASK");
+
+	kip = procstat_getprocs(procstat, KERN_PROC_PID | KERN_PROC_INC_THREAD,
+	    kipp->ki_pid, &count);
+	if (kip == NULL)
+		return;
+	kinfo_proc_sort(kip, count);
+	for (i = 0; i < count; i++) {
+		kipp = &kip[i];
+		printf("%5d ", kipp->ki_pid);
+		printf("%6d ", kipp->ki_tid);
+		printf("%-16s ", strlen(kipp->ki_comm) ?
+		    kipp->ki_comm : "-");
+		printf("%-16s ", (strlen(kipp->ki_tdname) &&
+		    (strcmp(kipp->ki_comm, kipp->ki_tdname) != 0)) ?
+		    kipp->ki_tdname : "-");
+		if (kipp->ki_oncpu != 255)
+			printf("%3d ", kipp->ki_oncpu);
+		else if (kipp->ki_lastcpu != 255)
+			printf("%3d ", kipp->ki_lastcpu);
+		else
+			printf("%3s ", "-");
+		if (cpuset_getid(CPU_LEVEL_CPUSET, CPU_WHICH_TID,
+		    kipp->ki_tid, &cs) != 0) {
+			cs = CPUSET_INVALID;
+		}
+		printf("%4d ", cs);
+		if ((cs != CPUSET_INVALID) && 
+		    (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID,
+		    kipp->ki_tid, sizeof(mask), &mask) == 0)) {
+			lastcpu = -1;
+			once = 0;
+			twice = 0;
+			for (cpu = 0; cpu < CPU_SETSIZE; cpu++) {
+				if (CPU_ISSET(cpu, &mask)) {
+					if (once == 0) {
+						printf("%d", cpu);
+						once = 1;
+					} else if (cpu == lastcpu + 1) {
+						twice = 1;
+					} else if (twice == 1) {
+						printf("-%d,%d", lastcpu, cpu);
+						twice = 0;
+					} else
+						printf(",%d", cpu);
+					lastcpu = cpu;
+				}
+			}
+			if (once && twice)
+				printf("-%d", lastcpu);
+		}
+		printf("\n");
+	}
+	procstat_freeprocs(procstat, kip);
+}