diff --git a/builder/fscache/fscache.go b/builder/fscache/fscache.go
index faef7d1ac1..880cc9d10d 100644
--- a/builder/fscache/fscache.go
+++ b/builder/fscache/fscache.go
@@ -1,7 +1,10 @@
 package fscache
 
 import (
+	"archive/tar"
+	"crypto/sha256"
 	"encoding/json"
+	"hash"
 	"os"
 	"path/filepath"
 	"sort"
@@ -11,8 +14,10 @@ import (
 	"github.com/boltdb/bolt"
 	"github.com/docker/docker/builder"
 	"github.com/docker/docker/builder/remotecontext"
+	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/directory"
 	"github.com/docker/docker/pkg/stringid"
+	"github.com/docker/docker/pkg/tarsum"
 	"github.com/moby/buildkit/session/filesync"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -578,6 +583,10 @@ func (dc *detectChanges) MarkSupported(v bool) {
 	dc.supported = v
 }
 
+func (dc *detectChanges) ContentHasher() fsutil.ContentHasher {
+	return newTarsumHash
+}
+
 type wrappedContext struct {
 	builder.Source
 	closer func() error
@@ -607,3 +616,40 @@ func (s sortableCacheSources) Less(i, j int) bool {
 func (s sortableCacheSources) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }
+
+func newTarsumHash(stat *fsutil.Stat) (hash.Hash, error) {
+	fi := &fsutil.StatInfo{stat}
+	p := stat.Path
+	if fi.IsDir() {
+		p += string(os.PathSeparator)
+	}
+	h, err := archive.FileInfoHeader(p, fi, stat.Linkname)
+	if err != nil {
+		return nil, err
+	}
+	h.Name = p
+	h.Uid = int(stat.Uid)
+	h.Gid = int(stat.Gid)
+	h.Linkname = stat.Linkname
+	if stat.Xattrs != nil {
+		h.Xattrs = make(map[string]string)
+		for k, v := range stat.Xattrs {
+			h.Xattrs[k] = string(v)
+		}
+	}
+
+	tsh := &tarsumHash{h: h, Hash: sha256.New()}
+	tsh.Reset()
+	return tsh, nil
+}
+
+// Reset resets the Hash to its initial state.
+func (tsh *tarsumHash) Reset() {
+	tsh.Hash.Reset()
+	tarsum.WriteV1Header(tsh.h, tsh.Hash)
+}
+
+type tarsumHash struct {
+	hash.Hash
+	h *tar.Header
+}
diff --git a/builder/remotecontext/tarsum.go b/builder/remotecontext/tarsum.go
index 6770eed871..370f13d80b 100644
--- a/builder/remotecontext/tarsum.go
+++ b/builder/remotecontext/tarsum.go
@@ -5,15 +5,15 @@ import (
 	"os"
 	"sync"
 
-	iradix "github.com/hashicorp/go-immutable-radix"
-
 	"github.com/docker/docker/pkg/containerfs"
+	iradix "github.com/hashicorp/go-immutable-radix"
+	digest "github.com/opencontainers/go-digest"
 	"github.com/pkg/errors"
 	"github.com/tonistiigi/fsutil"
 )
 
 type hashed interface {
-	Hash() string
+	Digest() digest.Digest
 }
 
 // CachableSource is a source that contains cache records for its contents
@@ -110,7 +110,7 @@ func (cs *CachableSource) HandleChange(kind fsutil.ChangeKind, p string, fi os.F
 	}
 
 	hfi := &fileInfo{
-		sum: h.Hash(),
+		sum: h.Digest().Hex(),
 	}
 	cs.txn.Insert([]byte(p), hfi)
 	cs.mu.Unlock()
diff --git a/integration-cli/docker_api_build_test.go b/integration-cli/docker_api_build_test.go
index 423ebcf9fc..8c494f1427 100644
--- a/integration-cli/docker_api_build_test.go
+++ b/integration-cli/docker_api_build_test.go
@@ -586,7 +586,9 @@ func testBuildWithSession(c *check.C, dir, dockerfile string) (outStr string) {
 	sess, err := session.NewSession("foo1", "foo")
 	assert.Nil(c, err)
 
-	fsProvider := filesync.NewFSSyncProvider(dir, nil)
+	fsProvider := filesync.NewFSSyncProvider([]filesync.SyncedDir{
+		{Dir: dir},
+	})
 	sess.Allow(fsProvider)
 
 	g, ctx := errgroup.WithContext(context.Background())
@@ -596,7 +598,7 @@ func testBuildWithSession(c *check.C, dir, dockerfile string) (outStr string) {
 	})
 
 	g.Go(func() error {
-		res, body, err := request.Post("/build?remote=client-session&session="+sess.UUID(), func(req *http.Request) error {
+		res, body, err := request.Post("/build?remote=client-session&session="+sess.ID(), func(req *http.Request) error {
 			req.Body = ioutil.NopCloser(strings.NewReader(dockerfile))
 			return nil
 		})
diff --git a/vendor.conf b/vendor.conf
index 98689c4b0b..246fdc14cc 100644
--- a/vendor.conf
+++ b/vendor.conf
@@ -27,7 +27,7 @@ github.com/imdario/mergo 0.2.1
 golang.org/x/sync de49d9dcd27d4f764488181bea099dfe6179bcf0
 
 github.com/containerd/continuity 22694c680ee48fb8f50015b44618517e2bde77e8
-github.com/moby/buildkit c2dbdeb457ea665699a5d97f79eebfac4ab4726f https://github.com/tonistiigi/buildkit.git
+github.com/moby/buildkit aaff9d591ef128560018433fe61beb802e149de8
 github.com/tonistiigi/fsutil 1dedf6e90084bd88c4c518a15e68a37ed1370203
 
 #get libnetwork packages