diff --git a/include/sys/bpobj.h b/include/sys/bpobj.h
index 16e403526c..2bca0a82e5 100644
--- a/include/sys/bpobj.h
+++ b/include/sys/bpobj.h
@@ -87,6 +87,7 @@ int livelist_bpobj_iterate_from_nofree(bpobj_t *bpo, bpobj_itor_t func,
     void *arg, int64_t start);
 
 void bpobj_enqueue_subobj(bpobj_t *bpo, uint64_t subobj, dmu_tx_t *tx);
+void bpobj_prefetch_subobj(bpobj_t *bpo, uint64_t subobj);
 void bpobj_enqueue(bpobj_t *bpo, const blkptr_t *bp, boolean_t bp_freed,
     dmu_tx_t *tx);
 
diff --git a/module/zfs/bpobj.c b/module/zfs/bpobj.c
index 68f534c6b1..a8e9309d28 100644
--- a/module/zfs/bpobj.c
+++ b/module/zfs/bpobj.c
@@ -663,14 +663,13 @@ bpobj_enqueue_subobj(bpobj_t *bpo, uint64_t subobj, dmu_tx_t *tx)
 	}
 
 	VERIFY3U(0, ==, bpobj_open(&subbpo, bpo->bpo_os, subobj));
-	VERIFY3U(0, ==, bpobj_space(&subbpo, &used, &comp, &uncomp));
-
 	if (bpobj_is_empty(&subbpo)) {
 		/* No point in having an empty subobj. */
 		bpobj_close(&subbpo);
 		bpobj_free(bpo->bpo_os, subobj, tx);
 		return;
 	}
+	VERIFY3U(0, ==, bpobj_space(&subbpo, &used, &comp, &uncomp));
 
 	mutex_enter(&bpo->bpo_lock);
 	dmu_buf_will_dirty(bpo->bpo_dbuf, tx);
@@ -780,6 +779,68 @@ bpobj_enqueue_subobj(bpobj_t *bpo, uint64_t subobj, dmu_tx_t *tx)
 
 }
 
+/*
+ * Prefetch metadata required for bpobj_enqueue_subobj().
+ */
+void
+bpobj_prefetch_subobj(bpobj_t *bpo, uint64_t subobj)
+{
+	dmu_object_info_t doi;
+	bpobj_t subbpo;
+	uint64_t subsubobjs;
+	boolean_t copy_subsub = B_TRUE;
+	boolean_t copy_bps = B_TRUE;
+
+	ASSERT(bpobj_is_open(bpo));
+	ASSERT(subobj != 0);
+
+	if (subobj == dmu_objset_pool(bpo->bpo_os)->dp_empty_bpobj)
+		return;
+
+	if (bpobj_open(&subbpo, bpo->bpo_os, subobj) != 0)
+		return;
+	if (bpobj_is_empty(&subbpo)) {
+		bpobj_close(&subbpo);
+		return;
+	}
+	subsubobjs = subbpo.bpo_phys->bpo_subobjs;
+	bpobj_close(&subbpo);
+
+	if (subsubobjs != 0) {
+		if (dmu_object_info(bpo->bpo_os, subsubobjs, &doi) != 0)
+			return;
+		if (doi.doi_max_offset > doi.doi_data_block_size)
+			copy_subsub = B_FALSE;
+	}
+
+	if (dmu_object_info(bpo->bpo_os, subobj, &doi) != 0)
+		return;
+	if (doi.doi_max_offset > doi.doi_data_block_size || !copy_subsub)
+		copy_bps = B_FALSE;
+
+	if (copy_subsub && subsubobjs != 0) {
+		if (bpo->bpo_phys->bpo_subobjs) {
+			dmu_prefetch(bpo->bpo_os, bpo->bpo_phys->bpo_subobjs, 0,
+			    bpo->bpo_phys->bpo_num_subobjs * sizeof (subobj), 1,
+			    ZIO_PRIORITY_ASYNC_READ);
+		}
+		dmu_prefetch(bpo->bpo_os, subsubobjs, 0, 0, 1,
+		    ZIO_PRIORITY_ASYNC_READ);
+	}
+
+	if (copy_bps) {
+		dmu_prefetch(bpo->bpo_os, bpo->bpo_object, 0,
+		    bpo->bpo_phys->bpo_num_blkptrs * sizeof (blkptr_t), 1,
+		    ZIO_PRIORITY_ASYNC_READ);
+		dmu_prefetch(bpo->bpo_os, subobj, 0, 0, 1,
+		    ZIO_PRIORITY_ASYNC_READ);
+	} else if (bpo->bpo_phys->bpo_subobjs) {
+		dmu_prefetch(bpo->bpo_os, bpo->bpo_phys->bpo_subobjs, 0,
+		    bpo->bpo_phys->bpo_num_subobjs * sizeof (subobj), 1,
+		    ZIO_PRIORITY_ASYNC_READ);
+	}
+}
+
 void
 bpobj_enqueue(bpobj_t *bpo, const blkptr_t *bp, boolean_t bp_freed,
     dmu_tx_t *tx)
diff --git a/module/zfs/dsl_deadlist.c b/module/zfs/dsl_deadlist.c
index 7681b735ec..1b2d8b92f2 100644
--- a/module/zfs/dsl_deadlist.c
+++ b/module/zfs/dsl_deadlist.c
@@ -438,6 +438,18 @@ dle_enqueue_subobj(dsl_deadlist_t *dl, dsl_deadlist_entry_t *dle,
 	}
 }
 
+/*
+ * Prefetch metadata required for dle_enqueue_subobj().
+ */
+static void
+dle_prefetch_subobj(dsl_deadlist_t *dl, dsl_deadlist_entry_t *dle,
+    uint64_t obj)
+{
+	if (dle->dle_bpobj.bpo_object !=
+	    dmu_objset_pool(dl->dl_os)->dp_empty_bpobj)
+		bpobj_prefetch_subobj(&dle->dle_bpobj, obj);
+}
+
 void
 dsl_deadlist_insert(dsl_deadlist_t *dl, const blkptr_t *bp, boolean_t bp_freed,
     dmu_tx_t *tx)
@@ -809,6 +821,27 @@ dsl_deadlist_insert_bpobj(dsl_deadlist_t *dl, uint64_t obj, uint64_t birth,
 	dle_enqueue_subobj(dl, dle, obj, tx);
 }
 
+/*
+ * Prefetch metadata required for dsl_deadlist_insert_bpobj().
+ */
+static void
+dsl_deadlist_prefetch_bpobj(dsl_deadlist_t *dl, uint64_t obj, uint64_t birth)
+{
+	dsl_deadlist_entry_t dle_tofind;
+	dsl_deadlist_entry_t *dle;
+	avl_index_t where;
+
+	ASSERT(MUTEX_HELD(&dl->dl_lock));
+
+	dsl_deadlist_load_tree(dl);
+
+	dle_tofind.dle_mintxg = birth;
+	dle = avl_find(&dl->dl_tree, &dle_tofind, &where);
+	if (dle == NULL)
+		dle = avl_nearest(&dl->dl_tree, where, AVL_BEFORE);
+	dle_prefetch_subobj(dl, dle, obj);
+}
+
 static int
 dsl_deadlist_insert_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed,
     dmu_tx_t *tx)
@@ -825,12 +858,12 @@ dsl_deadlist_insert_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed,
 void
 dsl_deadlist_merge(dsl_deadlist_t *dl, uint64_t obj, dmu_tx_t *tx)
 {
-	zap_cursor_t zc;
-	zap_attribute_t za;
+	zap_cursor_t zc, pzc;
+	zap_attribute_t za, pza;
 	dmu_buf_t *bonus;
 	dsl_deadlist_phys_t *dlp;
 	dmu_object_info_t doi;
-	int error;
+	int error, perror, i;
 
 	VERIFY0(dmu_object_info(dl->dl_os, obj, &doi));
 	if (doi.doi_type == DMU_OT_BPOBJ) {
@@ -842,15 +875,32 @@ dsl_deadlist_merge(dsl_deadlist_t *dl, uint64_t obj, dmu_tx_t *tx)
 	}
 
 	mutex_enter(&dl->dl_lock);
+	/*
+	 * Prefetch up to 128 deadlists first and then more as we progress.
+	 * The limit is a balance between ARC use and diminishing returns.
+	 */
+	for (zap_cursor_init(&pzc, dl->dl_os, obj), i = 0;
+	    (perror = zap_cursor_retrieve(&pzc, &pza)) == 0 && i < 128;
+	    zap_cursor_advance(&pzc), i++) {
+		dsl_deadlist_prefetch_bpobj(dl, pza.za_first_integer,
+		    zfs_strtonum(pza.za_name, NULL));
+	}
 	for (zap_cursor_init(&zc, dl->dl_os, obj);
 	    (error = zap_cursor_retrieve(&zc, &za)) == 0;
 	    zap_cursor_advance(&zc)) {
 		uint64_t mintxg = zfs_strtonum(za.za_name, NULL);
 		dsl_deadlist_insert_bpobj(dl, za.za_first_integer, mintxg, tx);
 		VERIFY0(zap_remove_int(dl->dl_os, obj, mintxg, tx));
+		if (perror == 0) {
+			dsl_deadlist_prefetch_bpobj(dl, pza.za_first_integer,
+			    zfs_strtonum(pza.za_name, NULL));
+			zap_cursor_advance(&pzc);
+			perror = zap_cursor_retrieve(&pzc, &pza);
+		}
 	}
 	VERIFY3U(error, ==, ENOENT);
 	zap_cursor_fini(&zc);
+	zap_cursor_fini(&pzc);
 
 	VERIFY0(dmu_bonus_hold(dl->dl_os, obj, FTAG, &bonus));
 	dlp = bonus->db_data;
@@ -868,8 +918,9 @@ dsl_deadlist_move_bpobj(dsl_deadlist_t *dl, bpobj_t *bpo, uint64_t mintxg,
     dmu_tx_t *tx)
 {
 	dsl_deadlist_entry_t dle_tofind;
-	dsl_deadlist_entry_t *dle;
+	dsl_deadlist_entry_t *dle, *pdle;
 	avl_index_t where;
+	int i;
 
 	ASSERT(!dl->dl_oldfmt);
 
@@ -881,11 +932,23 @@ dsl_deadlist_move_bpobj(dsl_deadlist_t *dl, bpobj_t *bpo, uint64_t mintxg,
 	dle = avl_find(&dl->dl_tree, &dle_tofind, &where);
 	if (dle == NULL)
 		dle = avl_nearest(&dl->dl_tree, where, AVL_AFTER);
+	/*
+	 * Prefetch up to 128 deadlists first and then more as we progress.
+	 * The limit is a balance between ARC use and diminishing returns.
+	 */
+	for (pdle = dle, i = 0; pdle && i < 128; ) {
+		bpobj_prefetch_subobj(bpo, pdle->dle_bpobj.bpo_object);
+		pdle = AVL_NEXT(&dl->dl_tree, pdle);
+	}
 	while (dle) {
 		uint64_t used, comp, uncomp;
 		dsl_deadlist_entry_t *dle_next;
 
 		bpobj_enqueue_subobj(bpo, dle->dle_bpobj.bpo_object, tx);
+		if (pdle) {
+			bpobj_prefetch_subobj(bpo, pdle->dle_bpobj.bpo_object);
+			pdle = AVL_NEXT(&dl->dl_tree, pdle);
+		}
 
 		VERIFY0(bpobj_space(&dle->dle_bpobj,
 		    &used, &comp, &uncomp));