diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
index 7eac42ce3630..dea1a8fa7bf1 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
@@ -155,6 +155,15 @@ static vdev_ops_t *vdev_ops_table[] = {
 };
 
 
+/*
+ * When a vdev is added, it will be divided into approximately (but no
+ * more than) this number of metaslabs.
+ */
+int metaslabs_per_vdev = 200;
+SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, metaslabs_per_vdev, CTLFLAG_RDTUN,
+    &metaslabs_per_vdev, 0,
+    "When a vdev is added, how many metaslabs the vdev should be divided into");
+
 /*
  * Given a vdev type, return the appropriate ops vector.
  */
@@ -1663,9 +1672,9 @@ void
 vdev_metaslab_set_size(vdev_t *vd)
 {
 	/*
-	 * Aim for roughly 200 metaslabs per vdev.
+	 * Aim for roughly metaslabs_per_vdev (default 200) metaslabs per vdev.
 	 */
-	vd->vdev_ms_shift = highbit64(vd->vdev_asize / 200);
+	vd->vdev_ms_shift = highbit64(vd->vdev_asize / metaslabs_per_vdev);
 	vd->vdev_ms_shift = MAX(vd->vdev_ms_shift, SPA_MAXBLOCKSHIFT);
 }