diff --git a/packer/build.go b/packer/build.go
index be1bf05b9..7a1723da4 100644
--- a/packer/build.go
+++ b/packer/build.go
@@ -8,6 +8,7 @@ type Build interface {
 	Name() string
 	Prepare(Ui) error
 	Run(Ui) Artifact
+	Cancel()
 }
 
 // A build struct represents a single build job, the result of which should
@@ -87,3 +88,7 @@ func (b *coreBuild) Run(ui Ui) Artifact {
 	hook := &DispatchHook{hooks}
 	return b.builder.Run(ui, hook)
 }
+
+// Cancels the build if it is running.
+func (b *coreBuild) Cancel() {
+}
diff --git a/packer/rpc/build.go b/packer/rpc/build.go
index 189defe75..e8f0efed5 100644
--- a/packer/rpc/build.go
+++ b/packer/rpc/build.go
@@ -68,6 +68,12 @@ func (b *build) Run(ui packer.Ui) packer.Artifact {
 	return Artifact(client)
 }
 
+func (b *build) Cancel() {
+	if err := b.client.Call("Build.Cancel", new(interface{}), new(interface{})); err != nil {
+		panic(err)
+	}
+}
+
 func (b *BuildServer) Name(args *interface{}, reply *string) error {
 	*reply = b.build.Name()
 	return nil
@@ -98,3 +104,8 @@ func (b *BuildServer) Run(args *BuildRunArgs, reply *string) error {
 	*reply = serveSingleConn(server)
 	return nil
 }
+
+func (b *BuildServer) Cancel(args *interface{}, reply *interface{}) error {
+	b.build.Cancel()
+	return nil
+}
diff --git a/packer/rpc/build_test.go b/packer/rpc/build_test.go
index 371093e6f..387c187e4 100644
--- a/packer/rpc/build_test.go
+++ b/packer/rpc/build_test.go
@@ -15,6 +15,7 @@ type testBuild struct {
 	prepareUi     packer.Ui
 	runCalled     bool
 	runUi         packer.Ui
+	cancelCalled  bool
 }
 
 func (b *testBuild) Name() string {
@@ -34,6 +35,10 @@ func (b *testBuild) Run(ui packer.Ui) packer.Artifact {
 	return testBuildArtifact
 }
 
+func (b *testBuild) Cancel() {
+	b.cancelCalled = true
+}
+
 func TestBuildRPC(t *testing.T) {
 	assert := asserts.NewTestingAsserts(t, true)
 
@@ -70,6 +75,10 @@ func TestBuildRPC(t *testing.T) {
 		assert.True(ui.sayCalled, "say should be called")
 		assert.Equal(ui.sayMessage, "format", "message should be correct")
 	}
+
+	// Test Cancel
+	bClient.Cancel()
+	assert.True(b.cancelCalled, "cancel should be called")
 }
 
 func TestBuild_ImplementsBuild(t *testing.T) {