diff --git a/core/builder.go b/core/builder.go
index 76953ad048beac88b4b2ca99530fb84b87cf1986..2eb168a2135172e7a4722c1752a1541eaa973674 100644
--- a/core/builder.go
+++ b/core/builder.go
@@ -23,6 +23,7 @@ type NodeBuilder struct {
 	peerhost HostOption
 	repo     repo.Repo
 	built    bool
+	nilrepo  bool
 }
 
 func NewNodeBuilder() *NodeBuilder {
@@ -33,7 +34,7 @@ func NewNodeBuilder() *NodeBuilder {
 	}
 }
 
-func defaultRepo() (repo.Repo, error) {
+func defaultRepo(dstore ds.ThreadSafeDatastore) (repo.Repo, error) {
 	c := cfg.Config{}
 	priv, pub, err := ci.GenerateKeyPairWithReader(ci.RSA, 1024, rand.Reader)
 	if err != nil {
@@ -56,7 +57,7 @@ func defaultRepo() (repo.Repo, error) {
 	c.Identity.PrivKey = base64.StdEncoding.EncodeToString(privkeyb)
 
 	return &repo.Mock{
-		D: dsync.MutexWrap(ds.NewMapDatastore()),
+		D: dstore,
 		C: c,
 	}, nil
 }
@@ -86,13 +87,23 @@ func (nb *NodeBuilder) SetRepo(r repo.Repo) *NodeBuilder {
 	return nb
 }
 
+func (nb *NodeBuilder) NilRepo() *NodeBuilder {
+	nb.nilrepo = true
+	return nb
+}
+
 func (nb *NodeBuilder) Build(ctx context.Context) (*IpfsNode, error) {
 	if nb.built {
 		return nil, ErrAlreadyBuilt
 	}
 	nb.built = true
 	if nb.repo == nil {
-		r, err := defaultRepo()
+		var d ds.Datastore
+		d = ds.NewMapDatastore()
+		if nb.nilrepo {
+			d = ds.NewNullDatastore()
+		}
+		r, err := defaultRepo(dsync.MutexWrap(d))
 		if err != nil {
 			return nil, err
 		}
diff --git a/core/commands/add.go b/core/commands/add.go
index 2aad4a3b95a81d8b11e820179e16df7153c4e2d7..721858c62880019b3332d1e6065aad530277de48 100644
--- a/core/commands/add.go
+++ b/core/commands/add.go
@@ -58,6 +58,7 @@ remains to be implemented.
 		cmds.BoolOption(progressOptionName, "p", "Stream progress data"),
 		cmds.BoolOption(wrapOptionName, "w", "Wrap files with a directory object"),
 		cmds.BoolOption(trickleOptionName, "t", "Use trickle-dag format for dag generation"),
+		cmds.BoolOption("only-hash", "n", "Only chunk and hash the specified content, don't write to disk"),
 	},
 	PreRun: func(req cmds.Request) error {
 		if quiet, _, _ := req.Option("quiet").Bool(); quiet {
@@ -92,6 +93,16 @@ remains to be implemented.
 		progress, _, _ := req.Option(progressOptionName).Bool()
 		trickle, _, _ := req.Option(trickleOptionName).Bool()
 		wrap, _, _ := req.Option(wrapOptionName).Bool()
+		hash, _, _ := req.Option("only-hash").Bool()
+
+		if hash {
+			nilnode, err := core.NewNodeBuilder().NilRepo().Build(n.Context())
+			if err != nil {
+				res.SetError(err, cmds.ErrNormal)
+				return
+			}
+			n = nilnode
+		}
 
 		outChan := make(chan interface{}, 8)
 		res.SetOutput((<-chan interface{})(outChan))