diff --git a/include/sys/arc_impl.h b/include/sys/arc_impl.h
index 43818d4104c4..db6238fda61e 100644
--- a/include/sys/arc_impl.h
+++ b/include/sys/arc_impl.h
@@ -30,6 +30,7 @@
 #define	_SYS_ARC_IMPL_H
 
 #include <sys/arc.h>
+#include <sys/multilist.h>
 #include <sys/zio_crypt.h>
 #include <sys/zthr.h>
 #include <sys/aggsum.h>
diff --git a/module/zfs/dmu_zfetch.c b/module/zfs/dmu_zfetch.c
index bca881d82f87..d2985d572975 100644
--- a/module/zfs/dmu_zfetch.c
+++ b/module/zfs/dmu_zfetch.c
@@ -28,6 +28,7 @@
  */
 
 #include <sys/zfs_context.h>
+#include <sys/arc_impl.h>
 #include <sys/dnode.h>
 #include <sys/dmu_objset.h>
 #include <sys/dmu_zfetch.h>
@@ -65,13 +66,15 @@ typedef struct zfetch_stats {
 	kstat_named_t zfetchstat_misses;
 	kstat_named_t zfetchstat_max_streams;
 	kstat_named_t zfetchstat_io_issued;
+	kstat_named_t zfetchstat_io_active;
 } zfetch_stats_t;
 
 static zfetch_stats_t zfetch_stats = {
 	{ "hits",			KSTAT_DATA_UINT64 },
 	{ "misses",			KSTAT_DATA_UINT64 },
 	{ "max_streams",		KSTAT_DATA_UINT64 },
-	{ "io_issued",		KSTAT_DATA_UINT64 },
+	{ "io_issued",			KSTAT_DATA_UINT64 },
+	{ "io_active",			KSTAT_DATA_UINT64 },
 };
 
 struct {
@@ -79,6 +82,7 @@ struct {
 	wmsum_t zfetchstat_misses;
 	wmsum_t zfetchstat_max_streams;
 	wmsum_t zfetchstat_io_issued;
+	aggsum_t zfetchstat_io_active;
 } zfetch_sums;
 
 #define	ZFETCHSTAT_BUMP(stat)					\
@@ -104,6 +108,8 @@ zfetch_kstats_update(kstat_t *ksp, int rw)
 	    wmsum_value(&zfetch_sums.zfetchstat_max_streams);
 	zs->zfetchstat_io_issued.value.ui64 =
 	    wmsum_value(&zfetch_sums.zfetchstat_io_issued);
+	zs->zfetchstat_io_active.value.ui64 =
+	    aggsum_value(&zfetch_sums.zfetchstat_io_active);
 	return (0);
 }
 
@@ -114,6 +120,7 @@ zfetch_init(void)
 	wmsum_init(&zfetch_sums.zfetchstat_misses, 0);
 	wmsum_init(&zfetch_sums.zfetchstat_max_streams, 0);
 	wmsum_init(&zfetch_sums.zfetchstat_io_issued, 0);
+	aggsum_init(&zfetch_sums.zfetchstat_io_active, 0);
 
 	zfetch_ksp = kstat_create("zfs", 0, "zfetchstats", "misc",
 	    KSTAT_TYPE_NAMED, sizeof (zfetch_stats) / sizeof (kstat_named_t),
@@ -138,6 +145,8 @@ zfetch_fini(void)
 	wmsum_fini(&zfetch_sums.zfetchstat_misses);
 	wmsum_fini(&zfetch_sums.zfetchstat_max_streams);
 	wmsum_fini(&zfetch_sums.zfetchstat_io_issued);
+	ASSERT0(aggsum_value(&zfetch_sums.zfetchstat_io_active));
+	aggsum_fini(&zfetch_sums.zfetchstat_io_active);
 }
 
 /*
@@ -294,6 +303,7 @@ dmu_zfetch_done(void *arg, uint64_t level, uint64_t blkid, boolean_t io_issued)
 		zs->zs_more = B_TRUE;
 	if (zfs_refcount_remove(&zs->zs_refs, NULL) == 0)
 		dmu_zfetch_stream_fini(zs);
+	aggsum_add(&zfetch_sums.zfetchstat_io_active, -1);
 }
 
 /*
@@ -407,20 +417,28 @@ dmu_zfetch_prepare(zfetch_t *zf, uint64_t blkid, uint64_t nblks,
 	 * Start prefetch from the demand access size (nblks).  Double the
 	 * distance every access up to zfetch_min_distance.  After that only
 	 * if needed increase the distance by 1/8 up to zfetch_max_distance.
+	 *
+	 * Don't double the distance beyond single block if we have more
+	 * than ~6% of ARC held by active prefetches.  It should help with
+	 * getting out of RAM on some badly mispredicted read patterns.
 	 */
-	unsigned int nbytes = nblks << zf->zf_dnode->dn_datablkshift;
+	unsigned int dbs = zf->zf_dnode->dn_datablkshift;
+	unsigned int nbytes = nblks << dbs;
 	unsigned int pf_nblks;
 	if (fetch_data) {
 		if (unlikely(zs->zs_pf_dist < nbytes))
 			zs->zs_pf_dist = nbytes;
-		else if (zs->zs_pf_dist < zfetch_min_distance)
+		else if (zs->zs_pf_dist < zfetch_min_distance &&
+		    (zs->zs_pf_dist < (1 << dbs) ||
+		    aggsum_compare(&zfetch_sums.zfetchstat_io_active,
+		    arc_c_max >> (4 + dbs)) < 0))
 			zs->zs_pf_dist *= 2;
 		else if (zs->zs_more)
 			zs->zs_pf_dist += zs->zs_pf_dist / 8;
 		zs->zs_more = B_FALSE;
 		if (zs->zs_pf_dist > zfetch_max_distance)
 			zs->zs_pf_dist = zfetch_max_distance;
-		pf_nblks = zs->zs_pf_dist >> zf->zf_dnode->dn_datablkshift;
+		pf_nblks = zs->zs_pf_dist >> dbs;
 	} else {
 		pf_nblks = 0;
 	}
@@ -439,7 +457,7 @@ dmu_zfetch_prepare(zfetch_t *zf, uint64_t blkid, uint64_t nblks,
 		zs->zs_ipf_dist *= 2;
 	if (zs->zs_ipf_dist > zfetch_max_idistance)
 		zs->zs_ipf_dist = zfetch_max_idistance;
-	pf_nblks = zs->zs_ipf_dist >> zf->zf_dnode->dn_datablkshift;
+	pf_nblks = zs->zs_ipf_dist >> dbs;
 	if (zs->zs_ipf_start < zs->zs_pf_end)
 		zs->zs_ipf_start = zs->zs_pf_end;
 	if (zs->zs_ipf_end < zs->zs_pf_end + pf_nblks)
@@ -509,6 +527,7 @@ dmu_zfetch_run(zstream_t *zs, boolean_t missed, boolean_t have_lock)
 			dmu_zfetch_stream_fini(zs);
 		return;
 	}
+	aggsum_add(&zfetch_sums.zfetchstat_io_active, issued);
 
 	if (!have_lock)
 		rw_enter(&zf->zf_dnode->dn_struct_rwlock, RW_READER);