diff --git a/sys/compat/linux/linux_misc.c b/sys/compat/linux/linux_misc.c
--- a/sys/compat/linux/linux_misc.c
+++ b/sys/compat/linux/linux_misc.c
@@ -62,6 +62,7 @@
 #include <security/mac/mac_framework.h>
 
 #include <vm/pmap.h>
+#include <vm/vm_param.h>
 #include <vm/vm_map.h>
 #include <vm/swap_pager.h>
 
@@ -324,6 +325,14 @@
 	args->old_len = round_page(args->old_len);
 
 	if (args->new_len > args->old_len) {
+		vm_offset_t new_addr = args->addr;
+
+		if (vm_mremap(td, &new_addr, args->new_len, args->addr,
+			args->old_len, args->flags) == KERN_SUCCESS) {
+			td->td_retval[0] = (uintptr_t)new_addr;
+			return 0;
+		}
+
 		td->td_retval[0] = 0;
 		return (ENOMEM);
 	}
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
@@ -534,5 +534,7 @@
     int flags);
 long vmspace_swap_count(struct vmspace *vmspace);
 void vm_map_entry_set_vnode_text(vm_map_entry_t entry, bool add);
+int vm_mremap(struct thread *td, vm_offset_t *naddr,
+		size_t nsize, uintptr_t oaddr, size_t osize, int flags);
 #endif				/* _KERNEL */
 #endif				/* _VM_MAP_ */
diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -94,6 +94,8 @@
 #include <vm/vm_page.h>
 #include <vm/vnode_pager.h>
 
+#include <fs/tmpfs/tmpfs.h>
+
 #ifdef HWPMC_HOOKS
 #include <sys/pmckern.h>
 #endif
@@ -1678,3 +1680,74 @@
 		return (EINVAL);
 	}
 }
+
+int
+vm_mremap(struct thread *td, vm_offset_t *naddr,
+		size_t nsize, uintptr_t oaddr, size_t osize, int flags)
+{
+	struct vmspace *vms;
+	vm_map_entry_t entry;
+	vm_offset_t kva, ofs;
+	vm_object_t obj;
+	vm_pindex_t pindex;
+	vm_prot_t prot;
+	boolean_t wired;
+	vm_map_t map;
+	size_t size;
+	int rv, vnode;
+
+	vms = td->td_proc->p_vmspace;
+
+	kva = (vm_offset_t)oaddr;
+	ofs = kva & PAGE_MASK;
+	kva = trunc_page(kva);
+	size = round_page(osize + ofs);
+	map = &vms->vm_map;
+
+	rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
+			&obj, &pindex, &prot, &wired);
+
+	if (rv != KERN_SUCCESS)
+		goto out;
+
+	vm_map_lookup_done(map, entry);
+
+	vnode = (obj->backing_object || obj->handle
+		|| (obj->flags & OBJ_TMPFS));
+
+	if (vnode) {
+		vm_object_reference(obj);
+		rv = vm_mmap_object(map, naddr, nsize, prot, prot, MAP_SHARED,
+				obj, kva - entry->start, FALSE, td);
+	} else {
+		rv = vm_mmap_object(map, naddr, nsize, prot, prot,
+				MAP_PRIVATE | MAP_ANON,	NULL, 0, FALSE, td);
+		if (rv == KERN_SUCCESS) {
+			size_t n = 0;
+			int save;
+
+			save = vm_fault_disable_pagefaults();
+			for (n = 0; n < osize; n += PAGE_SIZE) {
+				rv = vm_fault(map, (*naddr) + n, prot,
+					VM_FAULT_NORMAL, NULL);
+				if (rv != KERN_SUCCESS) {
+					vm_fault_enable_pagefaults(save);
+					goto out;
+				}
+
+				rv = copyin((void *)(kva + n),
+					(void *)((*naddr) + n), PAGE_SIZE);
+				if (rv) {
+					vm_fault_enable_pagefaults(save);
+					return KERN_NO_ACCESS;
+				}
+			}
+			vm_fault_enable_pagefaults(save);
+		}
+	}
+
+	vm_map_remove(map, kva, kva + size);
+
+out:
+	return rv;
+}