diff --git a/sstxn/sstxn.go b/sstxn/sstxn.go
index ed47471c..008313d8 100644
--- a/sstxn/sstxn.go
+++ b/sstxn/sstxn.go
@@ -24,6 +24,7 @@
 package sstxn
 
 import (
+	"context"
 	"errors"
 	"fmt"
 
@@ -54,6 +55,8 @@ func (nilLogger) Criticalf(message string, args ...interface{}) {}
 
 var _ Logger = nilLogger{}
 
+var ErrTimeout = fmt.Errorf("transaction failed after retrying for 120 seconds")
+
 // A Runner applies operations as part of a transaction onto any number
 // of collections within a database. See the Run method for details.
 type Runner struct {
@@ -105,7 +108,7 @@ func NewRunner(db *mgo.Database, logger Logger) *Runner {
 //
 // Any number of transactions may be run concurrently, with one
 // runner or many.
-func (r *Runner) Run(ops []txn.Op, id bson.ObjectId, info interface{}) (err error) {
+func (r *Runner) Run(ctx context.Context, ops []txn.Op, id bson.ObjectId, info interface{}) (err error) {
 	const efmt = "error in transaction op %d: %s"
 	for i := range ops {
 		op := &ops[i]
@@ -133,21 +136,19 @@ func (r *Runner) Run(ops []txn.Op, id bson.ObjectId, info interface{}) (err erro
 		id = bson.NewObjectId()
 	}
 
-	// Sometimes the mongo server will return an error code 112 (write conflict).
-	// This is a signal the transaction needs to be retried.
-	// We'll retry 3 times but not forever.
-	for i := 0; i < 3; i++ {
-		err = r.runTxn(ops, id)
-		if err == errWriteConflict {
-			r.logger.Tracef("attempt %d retrying txn ops", i)
-			continue
+	for {
+		err := r.runTxn(ops, id)
+		if err != errWriteConflict {
+			return err
 		}
-		break
-	}
-	if err == errWriteConflict {
-		err = txn.ErrAborted
+		select {
+		case <-ctx.Done():
+			r.logger.Debugf("transaction cancelled by caller or timeout reached, ops '%+v'", ops)
+			return ctx.Err()
+		default:
+		}
+		r.logger.Tracef("retrying txn ops '%+v'", ops)
 	}
-	return err
 }
 
 func (r *Runner) runTxn(ops []txn.Op, id bson.ObjectId) error {
@@ -474,7 +475,7 @@ func (r *Runner) updateLog(ops []txn.Op, revnos []int64, txnId bson.ObjectId) er
 //
 // Saved documents are in the format:
 //
-//     {"_id": <txn id>, <collection>: {"d": [<doc id>, ...], "r": [<doc revno>, ...]}}
+//	{"_id": <txn id>, <collection>: {"d": [<doc id>, ...], "r": [<doc revno>, ...]}}
 //
 // The document revision is the value of the txn-revno field after
 // the change has been applied. Negative values indicate the document
diff --git a/sstxn/sstxn_test.go b/sstxn/sstxn_test.go
index 0ab53300..e16979b4 100644
--- a/sstxn/sstxn_test.go
+++ b/sstxn/sstxn_test.go
@@ -3,6 +3,7 @@
 package sstxn_test
 
 import (
+	"context"
 	"flag"
 	"fmt"
 	"sync"
@@ -152,17 +153,17 @@ func (s *S) TestDocExists(c *C) {
 		Assert: txn.DocMissing,
 	}}
 
-	err = s.runner.Run(exists, "", nil)
+	err = s.runner.Run(context.Background(), exists, "", nil)
 	c.Assert(err, IsNil)
-	err = s.runner.Run(missing, "", nil)
+	err = s.runner.Run(context.Background(), missing, "", nil)
 	c.Assert(err, Equals, txn.ErrAborted)
 
 	err = s.accounts.RemoveId(0)
 	c.Assert(err, IsNil)
 
-	err = s.runner.Run(exists, "", nil)
+	err = s.runner.Run(context.Background(), exists, "", nil)
 	c.Assert(err, Equals, txn.ErrAborted)
-	err = s.runner.Run(missing, "", nil)
+	err = s.runner.Run(context.Background(), missing, "", nil)
 	c.Assert(err, IsNil)
 }
 
@@ -181,7 +182,7 @@ func (s *S) TestInsert(c *C) {
 	// server side transactions, trying to insert a doc that already
 	// exists aborts the entire transaction, so we no longer hide
 	// that fact.
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, Equals, txn.ErrAborted)
 
 	var account Account
@@ -190,7 +191,7 @@ func (s *S) TestInsert(c *C) {
 	c.Assert(account.Balance, Equals, 300)
 
 	ops[0].Id = 1
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	err = s.accounts.FindId(1).One(&account)
@@ -215,7 +216,7 @@ func (s *S) TestInsertStructID(c *C) {
 		Insert: M{"balance": 800},
 	}}
 
-	err := s.runner.Run(ops, "", nil)
+	err := s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	n, err := s.accounts.Find(nil).Count()
@@ -233,7 +234,7 @@ func (s *S) TestRemove(c *C) {
 		Remove: true,
 	}}
 
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	err = s.accounts.FindId(0).One(nil)
@@ -241,7 +242,7 @@ func (s *S) TestRemove(c *C) {
 
 	// Removing a non-existing doc does not abort the transaction,
 	// so we preserve the behavior.
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 }
 
@@ -258,7 +259,7 @@ func (s *S) TestUpdate(c *C) {
 		Update: M{"$inc": M{"balance": 100}},
 	}}
 
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	var account Account
@@ -282,7 +283,7 @@ func (s *S) TestInsertUpdate(c *C) {
 		Update: M{"$inc": M{"balance": 100}},
 	}}
 
-	err := s.runner.Run(ops, "", nil)
+	err := s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	var account Account
@@ -295,7 +296,7 @@ func (s *S) TestInsertUpdate(c *C) {
 	// was causing the Update to happen, ignoring the invalid Insert.
 	// We no longer treat Insert as a no-op, so we don't
 	// run the Update.
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, Equals, txn.ErrAborted)
 
 	err = s.accounts.FindId(0).One(&account)
@@ -317,7 +318,7 @@ func (s *S) TestUpdateInsert(c *C) {
 		Insert: M{"balance": 200},
 	}}
 
-	err := s.runner.Run(ops, "", nil)
+	err := s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	var account Account
@@ -325,7 +326,7 @@ func (s *S) TestUpdateInsert(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(account.Balance, Equals, 200)
 
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	err = s.accounts.FindId(0).One(&account)
@@ -348,7 +349,7 @@ func (s *S) TestInsertRemoveInsert(c *C) {
 		Insert: M{"_id": 0, "balance": 300},
 	}}
 
-	err := s.runner.Run(ops, "", nil)
+	err := s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	var account Account
@@ -388,7 +389,7 @@ func (s *S) TestErrors(c *C) {
 	txn.SetChaos(txn.Chaos{KillChance: 1.0})
 	for _, op := range tests {
 		c.Logf("op: %v", op)
-		err := s.runner.Run([]txn.Op{op}, "", nil)
+		err := s.runner.Run(context.Background(), []txn.Op{op}, "", nil)
 		c.Assert(err, ErrorMatches, "error in transaction op 0: .*")
 	}
 }
@@ -401,7 +402,7 @@ func (s *S) TestAssertRefusesUpdate(c *C) {
 		Assert: bson.D{{"balance", 200}},
 		Update: bson.D{{"$inc", bson.D{{"balance", 100}}}},
 	}}
-	c.Assert(s.runner.Run(ops, "", nil), Equals, txn.ErrAborted)
+	c.Assert(s.runner.Run(context.Background(), ops, "", nil), Equals, txn.ErrAborted)
 	var account Account
 	c.Assert(s.accounts.FindId(0).One(&account), IsNil)
 	c.Assert(account.Balance, Equals, 100)
@@ -419,7 +420,7 @@ func (s *S) TestAssertNestedOr(c *C) {
 		Update: bson.D{{"$inc", bson.D{{"balance", 100}}}},
 	}}
 
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	var account Account
@@ -427,7 +428,7 @@ func (s *S) TestAssertNestedOr(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(account.Balance, Equals, 200)
 
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, Equals, txn.ErrAborted)
 
 	ops2 := []txn.Op{{
@@ -436,11 +437,11 @@ func (s *S) TestAssertNestedOr(c *C) {
 		Assert: bson.D{{"balance", 200}},
 		Update: bson.D{{"$set", bson.D{{"balance", 300}}}},
 	}}
-	err = s.runner.Run(ops2, "", nil)
+	err = s.runner.Run(context.Background(), ops2, "", nil)
 	c.Assert(err, IsNil)
 
 	// Now that we're at 300, the original ops should apply again
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	err = s.accounts.FindId(0).One(&account)
@@ -456,7 +457,7 @@ func (s *S) TestInsertInvalidAssert(c *C) {
 		Insert: bson.D{{"balance", 100}},
 	}}
 
-	err := s.runner.Run(ops, "", nil)
+	err := s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, ErrorMatches, `Insert can only Assert txn.DocMissing not \[\{balance 100\}\]`)
 
 	ops = []txn.Op{{
@@ -466,7 +467,7 @@ func (s *S) TestInsertInvalidAssert(c *C) {
 		Insert: bson.D{{"balance", 100}},
 	}}
 
-	err = s.runner.Run(ops, "", nil)
+	err = s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, ErrorMatches, "Insert can only Assert txn.DocMissing not txn.DocExists")
 }
 
@@ -480,7 +481,7 @@ func (s *S) TestVerifyFieldOrdering(c *C) {
 		Insert: fields,
 	}}
 
-	err := s.runner.Run(ops, "", nil)
+	err := s.runner.Run(context.Background(), ops, "", nil)
 	c.Assert(err, IsNil)
 
 	var d bson.D
@@ -522,7 +523,7 @@ func (s *S) TestChangeLog(c *C) {
 		Insert: M{"accounts": []int64{0, 1}},
 	}}
 	id := bson.NewObjectId()
-	err := s.runner.Run(ops, id, nil)
+	err := s.runner.Run(context.Background(), ops, id, nil)
 	c.Assert(err, IsNil)
 
 	type IdList []interface{}
@@ -548,7 +549,7 @@ func (s *S) TestChangeLog(c *C) {
 		Update: M{"$inc": M{"balance": 100}},
 	}}
 	id = bson.NewObjectId()
-	err = s.runner.Run(ops, id, nil)
+	err = s.runner.Run(context.Background(), ops, id, nil)
 	c.Assert(err, IsNil)
 
 	m = nil
@@ -568,7 +569,7 @@ func (s *S) TestChangeLog(c *C) {
 		Remove: true,
 	}}
 	id = bson.NewObjectId()
-	err = s.runner.Run(ops, id, nil)
+	err = s.runner.Run(context.Background(), ops, id, nil)
 	c.Assert(err, IsNil)
 
 	m = nil
@@ -613,7 +614,7 @@ func (s *S) TestInsertStressTest(c *C) {
 							"added-by": i,
 						},
 					}}
-					err := runner.Run(ops, "", nil)
+					err := runner.Run(context.Background(), ops, "", nil)
 					if err != txn.ErrAborted {
 						c.Check(err, IsNil)
 					}
@@ -643,7 +644,7 @@ func (s *S) TestConcurrentUpdateTest(c *C) {
 			for j := 0; j < count; j++ {
 				db := session.DB("test")
 				runner := sstxn.NewRunner(db, &testLogger{c})
-				err := runner.Run([]txn.Op{{
+				err := runner.Run(context.Background(), []txn.Op{{
 					C:      "accounts",
 					Id:     0,
 					Assert: txn.DocExists,
@@ -672,10 +673,10 @@ func (s *S) TestConcurrentInsertPreAssertFailure(c *C) {
 		Insert: bson.M{"foo": "bar"},
 	}}
 	runner1.SetStartHook(func() {
-		err := runner2.Run(ops, "", nil)
+		err := runner2.Run(context.Background(), ops, "", nil)
 		c.Check(err, IsNil)
 	})
-	err := runner1.Run(ops, "", nil)
+	err := runner1.Run(context.Background(), ops, "", nil)
 	c.Check(err, Equals, txn.ErrAborted)
 }
 
@@ -692,10 +693,10 @@ func (s *S) TestConcurrentInsertPostAssertFailure(c *C) {
 		Insert: bson.M{"foo": "bar"},
 	}}
 	runner1.SetPostAssertHook(func() {
-		err := runner2.Run(ops, "", nil)
+		err := runner2.Run(context.Background(), ops, "", nil)
 		c.Check(err, IsNil)
 	})
-	err := runner1.Run(ops, "", nil)
+	err := runner1.Run(context.Background(), ops, "", nil)
 	c.Check(err, Equals, txn.ErrAborted)
 }
 
@@ -705,14 +706,14 @@ func (s *S) TestConcurrentUpdatePreAssertFailure(c *C) {
 	session2 := s.session.Copy()
 	defer session2.Close()
 	runner2 := sstxn.NewRunner(s.db.With(session2), logger)
-	runner1.Run([]txn.Op{{
+	runner1.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Assert: txn.DocMissing,
 		Insert: bson.M{"balance": 0},
 	}}, "", nil)
 	runner1.SetStartHook(func() {
-		err := runner2.Run([]txn.Op{{
+		err := runner2.Run(context.Background(), []txn.Op{{
 			C:      "accounts",
 			Id:     0,
 			Assert: txn.DocExists,
@@ -720,7 +721,7 @@ func (s *S) TestConcurrentUpdatePreAssertFailure(c *C) {
 		}}, "", nil)
 		c.Check(err, IsNil)
 	})
-	err := runner1.Run([]txn.Op{{
+	err := runner1.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Assert: bson.M{"balance": 0},
@@ -735,14 +736,14 @@ func (s *S) TestConcurrentUpdatePostAssertFailure(c *C) {
 	session2 := s.session.Copy()
 	defer session2.Close()
 	runner2 := sstxn.NewRunner(s.db.With(session2), logger)
-	runner1.Run([]txn.Op{{
+	runner1.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Assert: txn.DocMissing,
 		Insert: bson.M{"balance": 0},
 	}}, "", nil)
 	runner1.SetPostAssertHook(func() {
-		err := runner2.Run([]txn.Op{{
+		err := runner2.Run(context.Background(), []txn.Op{{
 			C:      "accounts",
 			Id:     0,
 			Assert: txn.DocExists,
@@ -750,7 +751,7 @@ func (s *S) TestConcurrentUpdatePostAssertFailure(c *C) {
 		}}, "", nil)
 		c.Check(err, IsNil)
 	})
-	err := runner1.Run([]txn.Op{{
+	err := runner1.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Assert: bson.M{"balance": 0},
@@ -766,7 +767,7 @@ func (s *S) TestConcurrentRemoveUpdatePostAssertFailure(c *C) {
 	session2 := s.session.Copy()
 	defer session2.Close()
 	runner2 := sstxn.NewRunner(s.db.With(session2), logger)
-	err := runner1.Run([]txn.Op{{
+	err := runner1.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Assert: txn.DocMissing,
@@ -774,7 +775,7 @@ func (s *S) TestConcurrentRemoveUpdatePostAssertFailure(c *C) {
 	}}, "", nil)
 	c.Assert(err, IsNil)
 	runner1.SetPostAssertHook(func() {
-		err := runner2.Run([]txn.Op{{
+		err := runner2.Run(context.Background(), []txn.Op{{
 			C:      "accounts",
 			Id:     0,
 			Assert: txn.DocExists,
@@ -782,12 +783,14 @@ func (s *S) TestConcurrentRemoveUpdatePostAssertFailure(c *C) {
 		}}, "", nil)
 		c.Check(err, IsNil)
 	})
-	err = runner1.Run([]txn.Op{{
+	err = runner1.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Remove: true,
 	}}, "", nil)
-	c.Assert(err, Equals, txn.ErrAborted)
+	// Since we are getting a WriteConflict, we retry for 120 seconds
+	// and then fail with timeout error.
+	c.Assert(err, Equals, sstxn.ErrTimeout)
 }
 
 type NotMarshallable struct {
@@ -807,7 +810,7 @@ func (s *S) TestNotMarshallableUpdate(c *C) {
 	c.Assert(err, IsNil)
 	logger := &testLogger{c}
 	runner := sstxn.NewRunner(s.db, logger)
-	err = runner.Run([]txn.Op{{
+	err = runner.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Update: NotMarshallable{Error: fmt.Errorf("cannot marshall for update")},
@@ -824,7 +827,7 @@ func (s *S) TestNotMarshallableUpdate(c *C) {
 func (s *S) TestNotMarshallableInsert(c *C) {
 	logger := &testLogger{c}
 	runner := sstxn.NewRunner(s.db, logger)
-	err := runner.Run([]txn.Op{{
+	err := runner.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     0,
 		Insert: NotMarshallable{Error: fmt.Errorf("cannot marshall for insert")},
@@ -844,7 +847,7 @@ type testStruct struct {
 func (s *S) TestInsertValueFromStructForcedID(c *C) {
 	// If someone only sets the Value part of a document, we still want to make
 	// sure the _id of the inserted document is correct.
-	c.Assert(s.runner.Run([]txn.Op{{
+	c.Assert(s.runner.Run(context.Background(), []txn.Op{{
 		C:      "accounts",
 		Id:     "1",
 		Assert: txn.DocMissing,
diff --git a/txn/txn.go b/txn/txn.go
index bd6e0095..d91508c4 100644
--- a/txn/txn.go
+++ b/txn/txn.go
@@ -2,11 +2,11 @@
 //
 // For details check the following blog post:
 //
-//     http://blog.labix.org/2012/08/22/multi-doc-transactions-for-mongodb
-//
+//	http://blog.labix.org/2012/08/22/multi-doc-transactions-for-mongodb
 package txn
 
 import (
+	"context"
 	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
@@ -301,7 +301,7 @@ var ErrAborted = fmt.Errorf("transaction aborted")
 //
 // Any number of transactions may be run concurrently, with one
 // runner or many.
-func (r *Runner) Run(ops []Op, id bson.ObjectId, info interface{}) (err error) {
+func (r *Runner) Run(ctx context.Context, ops []Op, id bson.ObjectId, info interface{}) (err error) {
 	const efmt = "error in transaction op %d: %s"
 	for i := range ops {
 		op := &ops[i]
@@ -399,7 +399,7 @@ func (r *Runner) Resume(id bson.ObjectId) (err error) {
 //
 // Saved documents are in the format:
 //
-//     {"_id": <txn id>, <collection>: {"d": [<doc id>, ...], "r": [<doc revno>, ...]}}
+//	{"_id": <txn id>, <collection>: {"d": [<doc id>, ...], "r": [<doc revno>, ...]}}
 //
 // The document revision is the value of the txn-revno field after
 // the change has been applied. Negative values indicate the document