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
@@ -1978,23 +1978,30 @@
 static int cluster_anon = 1;
 SYSCTL_INT(_vm, OID_AUTO, cluster_anon, CTLFLAG_RW,
     &cluster_anon, 0,
-    "Cluster anonymous mappings: 0 = no, 1 = yes if no hint, 2 = always");
+    "Cluster anonymous mappings: "
+    "0 = no, 1 = yes if no hint, 2 = always, 3 = keep anon_loc const");
 
 static bool
-clustering_anon_allowed(vm_offset_t addr)
+clustering_anon_allowed(vm_offset_t addr, vm_offset_t anon_loc)
 {
 
 	switch (cluster_anon) {
 	case 0:
 		return (false);
 	case 1:
-		return (addr == 0);
+		return (addr == 0 || addr <= anon_loc);
 	case 2:
 	default:
 		return (true);
 	}
 }
 
+static bool
+clustering_anon_loc_const(void)
+{
+	return (cluster_anon == 3);
+}
+
 static long aslr_restarts;
 SYSCTL_LONG(_vm, OID_AUTO, aslr_restarts, CTLFLAG_RD,
     &aslr_restarts, 0,
@@ -2093,6 +2100,7 @@
 	    vm_size_t length, vm_offset_t max_addr, int find_space,
 	    vm_prot_t prot, vm_prot_t max, int cow)
 {
+	vm_map_entry_t entry;
 	vm_offset_t alignment, curr_min_addr, min_addr;
 	int gap, pidx, rv, try;
 	bool cluster, en_aslr, update_anon;
@@ -2111,7 +2119,7 @@
 	} else
 		alignment = 0;
 	en_aslr = (map->flags & MAP_ASLR) != 0;
-	update_anon = cluster = clustering_anon_allowed(*addr) &&
+	update_anon = cluster = clustering_anon_allowed(*addr, map->anon_loc) &&
 	    (map->flags & MAP_IS_SUB_MAP) == 0 && max_addr == 0 &&
 	    find_space != VMFS_NO_SPACE && object == NULL &&
 	    (cow & (MAP_INHERIT_SHARE | MAP_STACK_GROWS_UP |
@@ -2127,6 +2135,8 @@
 		curr_min_addr = map->anon_loc;
 		if (curr_min_addr == 0)
 			cluster = false;
+		else if (!vm_map_lookup_entry(map, curr_min_addr, &entry))
+			curr_min_addr = entry->end;
 	}
 	if (find_space != VMFS_NO_SPACE) {
 		KASSERT(find_space == VMFS_ANY_SPACE ||
@@ -2226,7 +2236,7 @@
 		rv = vm_map_insert(map, object, offset, *addr, *addr + length,
 		    prot, max, cow);
 	}
-	if (rv == KERN_SUCCESS && update_anon)
+	if (rv == KERN_SUCCESS && update_anon && !clustering_anon_loc_const())
 		map->anon_loc = *addr + length;
 done:
 	vm_map_unlock(map);
@@ -3966,7 +3976,7 @@
 		    entry->object.vm_object != NULL)
 			pmap_map_delete(map->pmap, entry->start, entry->end);
 
-		if (entry->end == map->anon_loc)
+		if (entry->end == map->anon_loc && !clustering_anon_loc_const())
 			map->anon_loc = entry->start;
 
 		/*