diff --git a/chain/store/index.go b/chain/store/index.go
index 7edbf251f..8f3e88417 100644
--- a/chain/store/index.go
+++ b/chain/store/index.go
@@ -2,6 +2,8 @@ package store
 
 import (
 	"context"
+	"os"
+	"strconv"
 
 	"github.com/filecoin-project/lotus/chain/types"
 	"github.com/filecoin-project/specs-actors/actors/abi"
@@ -9,6 +11,19 @@ import (
 	"golang.org/x/xerrors"
 )
 
+var DefaultChainIndexCacheSize = 32 << 10
+
+func init() {
+	if s := os.Getenv("LOTUS_CHAIN_INDEX_CACHE"); s != "" {
+		lcic, err := strconv.Atoi(s)
+		if err != nil {
+			log.Errorf("failed to parse 'LOTUS_CHAIN_INDEX_CACHE' env var: %s", err)
+		}
+		DefaultChainIndexCacheSize = lcic
+	}
+
+}
+
 type ChainIndex struct {
 	skipCache *lru.ARCCache
 
@@ -19,7 +34,7 @@ type ChainIndex struct {
 type loadTipSetFunc func(types.TipSetKey) (*types.TipSet, error)
 
 func NewChainIndex(lts loadTipSetFunc) *ChainIndex {
-	sc, _ := lru.NewARC(8192)
+	sc, _ := lru.NewARC(DefaultChainIndexCacheSize)
 	return &ChainIndex{
 		skipCache:  sc,
 		loadTipSet: lts,
diff --git a/chain/store/store.go b/chain/store/store.go
index d34fdbe5f..24d8c408b 100644
--- a/chain/store/store.go
+++ b/chain/store/store.go
@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"io"
 	"os"
+	"strconv"
 	"sync"
 
 	"github.com/filecoin-project/specs-actors/actors/crypto"
@@ -47,6 +48,18 @@ var log = logging.Logger("chainstore")
 var chainHeadKey = dstore.NewKey("head")
 var blockValidationCacheKeyPrefix = dstore.NewKey("blockValidation")
 
+var DefaultTipSetCacheSize = 8192
+
+func init() {
+	if s := os.Getenv("LOTUS_CHAIN_TIPSET_CACHE"); s != "" {
+		tscs, err := strconv.Atoi(s)
+		if err != nil {
+			log.Errorf("failed to parse 'LOTUS_CHAIN_TIPSET_CACHE' env var: %s", err)
+		}
+		DefaultTipSetCacheSize = tscs
+	}
+}
+
 // ReorgNotifee represents a callback that gets called upon reorgs.
 type ReorgNotifee func(rev, app []*types.TipSet) error
 
@@ -85,7 +98,7 @@ type ChainStore struct {
 
 func NewChainStore(bs bstore.Blockstore, ds dstore.Batching, vmcalls vm.SyscallBuilder) *ChainStore {
 	c, _ := lru.NewARC(2048)
-	tsc, _ := lru.NewARC(4096)
+	tsc, _ := lru.NewARC(DefaultTipSetCacheSize)
 	cs := &ChainStore{
 		bs:       bs,
 		ds:       ds,