diff --git a/lib/libkvm/kvm_proc.c b/lib/libkvm/kvm_proc.c
--- a/lib/libkvm/kvm_proc.c
+++ b/lib/libkvm/kvm_proc.c
@@ -320,6 +320,7 @@
 		(void)kvm_read(kd, (u_long)proc.p_vmspace,
 		    (char *)&vmspace, sizeof(vmspace));
 		kp->ki_size = vmspace.vm_map.size;
+		kp->ki_maxsize = vmspace.vm_map.max_size;
 		/*
 		 * Approximate the kernel's method of calculating
 		 * this field.
diff --git a/sys/compat/freebsd32/freebsd32.h b/sys/compat/freebsd32/freebsd32.h
--- a/sys/compat/freebsd32/freebsd32.h
+++ b/sys/compat/freebsd32/freebsd32.h
@@ -367,6 +367,7 @@
 	short	ki_spare_short2;
 	gid_t 	ki_groups[KI_NGROUPS];
 	uint32_t ki_size;
+	uint32_t ki_maxsize;
 	int32_t ki_rssize;
 	int32_t ki_swrss;
 	int32_t ki_tsize;
diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -1154,6 +1154,7 @@
 	 * implement it. Submissions are welcome.
 	 */
 	sbuf_printf(sb, "VmSize:\t%8ju kB\n",	B2K((uintmax_t)kp.ki_size));
+	sbuf_printf(sb, "VmPeak:\t%8ju kB\n",	B2K((uintmax_t)kp.ki_maxsize));
 	sbuf_printf(sb, "VmLck:\t%8u kB\n",	P2K(0)); /* XXX */
 	sbuf_printf(sb, "VmRSS:\t%8ju kB\n",	P2K((uintmax_t)kp.ki_rssize));
 	sbuf_printf(sb, "VmData:\t%8ju kB\n",	P2K((uintmax_t)kp.ki_dsize));
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -1139,6 +1139,7 @@
 		struct vmspace *vm = p->p_vmspace;
 
 		kp->ki_size = vm->vm_map.size;
+		kp->ki_maxsize = vm->vm_map.max_size;
 		kp->ki_rssize = vmspace_resident_count(vm); /*XXX*/
 		FOREACH_THREAD_IN_PROC(p, td0)
 			kp->ki_rssize += td0->td_kstack_pages;
@@ -1445,6 +1446,7 @@
 	for (i = 0; i < KI_NGROUPS; i++)
 		CP(*ki, *ki32, ki_groups[i]);
 	CP(*ki, *ki32, ki_size);
+	CP(*ki, *ki32, ki_maxsize);
 	CP(*ki, *ki32, ki_rssize);
 	CP(*ki, *ki32, ki_swrss);
 	CP(*ki, *ki32, ki_tsize);
diff --git a/sys/sys/user.h b/sys/sys/user.h
--- a/sys/sys/user.h
+++ b/sys/sys/user.h
@@ -84,7 +84,7 @@
  * function kvm_proclist in lib/libkvm/kvm_proc.c .
  */
 #define	KI_NSPARE_INT	2
-#define	KI_NSPARE_LONG	12
+#define	KI_NSPARE_LONG	11
 #define	KI_NSPARE_PTR	5
 
 #ifndef _KERNEL
@@ -213,6 +213,7 @@
 	struct	pwddesc *ki_pd;	/* pointer to process paths info */
 	void	*ki_spareptrs[KI_NSPARE_PTR];	/* spare room for growth */
 	long	ki_sparelongs[KI_NSPARE_LONG];	/* spare room for growth */
+	vm_size_t ki_maxsize;		/* maximum virtual size so far */
 	long	ki_sflag;		/* PS_* flags */
 	long	ki_tdflags;		/* XXXKSE kthread flag */
 };
diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h
--- a/sys/vm/vm_map.h
+++ b/sys/vm/vm_map.h
@@ -207,6 +207,7 @@
 	struct mtx system_mtx;
 	int nentries;			/* Number of entries */
 	vm_size_t size;			/* virtual size */
+	vm_size_t max_size;		/* Max of virtual size so far */
 	u_int timestamp;		/* Version number */
 	u_char needs_wakeup;
 	u_char system_map;		/* (c) Am I a system map? */
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -889,6 +889,7 @@
 {
 
 	map->header.eflags = MAP_ENTRY_HEADER;
+	map->max_size = 0;
 	map->needs_wakeup = FALSE;
 	map->system_map = 0;
 	map->pmap = pmap;
@@ -1812,8 +1813,11 @@
 	 * Insert the new entry into the list
 	 */
 	vm_map_entry_link(map, new_entry);
-	if ((new_entry->eflags & MAP_ENTRY_GUARD) == 0)
+	if ((new_entry->eflags & MAP_ENTRY_GUARD) == 0) {
 		map->size += new_entry->end - new_entry->start;
+		if (map->size > map->max_size)
+			map->max_size = map->size;
+	}
 
 	/*
 	 * Try to coalesce the new entry with both the previous and next
@@ -4327,6 +4331,8 @@
 		return;
 	entrysize = entry->end - entry->start;
 	vm2->vm_map.size += entrysize;
+	if (vm2->vm_map.size > vm2->vm_map.max_size)
+		vm2->vm_map.max_size = vm2->vm_map.size;
 	if (entry->eflags & (MAP_ENTRY_GROWS_DOWN | MAP_ENTRY_GROWS_UP)) {
 		vm2->vm_ssize += btoc(entrysize);
 	} else if (entry->start >= (vm_offset_t)vm1->vm_daddr &&