diff --git a/cmd/kube-proxy/app/server.go b/cmd/kube-proxy/app/server.go
index 0b753163a40..e42e31341e3 100644
--- a/cmd/kube-proxy/app/server.go
+++ b/cmd/kube-proxy/app/server.go
@@ -470,7 +470,7 @@ func NewProxyServer(config *componentconfig.KubeProxyConfiguration, cleanupAndEx
 			if err != nil {
 				return nil, fmt.Errorf("unable to create proxier: %v", err)
 			}
-			serviceHandler = proxierUserspace
+			serviceEventHandler = proxierUserspace
 			proxier = proxierUserspace
 		}
 		// Remove artifacts from the pure-iptables Proxier, if not on Windows.
diff --git a/pkg/proxy/userspace/proxier.go b/pkg/proxy/userspace/proxier.go
index ab62c9739cb..5032577b81f 100644
--- a/pkg/proxy/userspace/proxier.go
+++ b/pkg/proxy/userspace/proxier.go
@@ -395,97 +395,124 @@ func (proxier *Proxier) addServiceOnPort(service proxy.ServicePortName, protocol
 	return si, nil
 }
 
-// OnServiceUpdate manages the active set of service proxies.
-// Active service proxies are reinitialized if found in the update set or
-// shutdown if missing from the update set.
-func (proxier *Proxier) OnServiceUpdate(services []*api.Service) {
-	glog.V(4).Infof("Received update notice: %+v", services)
-	activeServices := make(map[proxy.ServicePortName]bool) // use a map as a set
-	for _, service := range services {
-		// if ClusterIP is "None" or empty, skip proxying
-		if !helper.IsServiceIPSet(service) {
-			glog.V(3).Infof("Skipping service %s due to clusterIP = %q", types.NamespacedName{Namespace: service.Namespace, Name: service.Name}, service.Spec.ClusterIP)
+func (proxier *Proxier) mergeService(service *api.Service) sets.String {
+	if service == nil {
+		return nil
+	}
+	svcName := types.NamespacedName{Namespace: service.Namespace, Name: service.Name}
+	if !helper.IsServiceIPSet(service) {
+		glog.V(3).Infof("Skipping service %s due to clusterIP = %q", svcName, service.Spec.ClusterIP)
+		return nil
+	}
+	existingPorts := sets.NewString()
+	for i := range service.Spec.Ports {
+		servicePort := &service.Spec.Ports[i]
+		serviceName := proxy.ServicePortName{NamespacedName: svcName, Port: servicePort.Name}
+		existingPorts.Insert(servicePort.Name)
+		info, exists := proxier.getServiceInfo(serviceName)
+		// TODO: check health of the socket? What if ProxyLoop exited?
+		if exists && sameConfig(info, service, servicePort) {
+			// Nothing changed.
+			continue
+		}
+		if exists {
+			glog.V(4).Infof("Something changed for service %q: stopping it", serviceName)
+			if err := proxier.closePortal(serviceName, info); err != nil {
+				glog.Errorf("Failed to close portal for %q: %v", serviceName, err)
+			}
+			if err := proxier.stopProxy(serviceName, info); err != nil {
+				glog.Errorf("Failed to stop service %q: %v", serviceName, err)
+			}
+		}
+		proxyPort, err := proxier.proxyPorts.AllocateNext()
+		if err != nil {
+			glog.Errorf("failed to allocate proxy port for service %q: %v", serviceName, err)
 			continue
 		}
 
-		for i := range service.Spec.Ports {
-			servicePort := &service.Spec.Ports[i]
-			serviceName := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: service.Namespace, Name: service.Name}, Port: servicePort.Name}
-			activeServices[serviceName] = true
-			serviceIP := net.ParseIP(service.Spec.ClusterIP)
-			info, exists := proxier.getServiceInfo(serviceName)
-			// TODO: check health of the socket?  What if ProxyLoop exited?
-			if exists && sameConfig(info, service, servicePort) {
-				// Nothing changed.
-				continue
-			}
-			if exists {
-				glog.V(4).Infof("Something changed for service %q: stopping it", serviceName)
-				err := proxier.closePortal(serviceName, info)
-				if err != nil {
-					glog.Errorf("Failed to close portal for %q: %v", serviceName, err)
-				}
-				err = proxier.stopProxy(serviceName, info)
-				if err != nil {
-					glog.Errorf("Failed to stop service %q: %v", serviceName, err)
-				}
-			}
-
-			proxyPort, err := proxier.proxyPorts.AllocateNext()
-			if err != nil {
-				glog.Errorf("failed to allocate proxy port for service %q: %v", serviceName, err)
-				continue
-			}
-
-			glog.V(1).Infof("Adding new service %q at %s:%d/%s", serviceName, serviceIP, servicePort.Port, servicePort.Protocol)
-			info, err = proxier.addServiceOnPort(serviceName, servicePort.Protocol, proxyPort, proxier.udpIdleTimeout)
-			if err != nil {
-				glog.Errorf("Failed to start proxy for %q: %v", serviceName, err)
-				continue
-			}
-			info.portal.ip = serviceIP
-			info.portal.port = int(servicePort.Port)
-			info.externalIPs = service.Spec.ExternalIPs
-			// Deep-copy in case the service instance changes
-			info.loadBalancerStatus = *helper.LoadBalancerStatusDeepCopy(&service.Status.LoadBalancer)
-			info.nodePort = int(servicePort.NodePort)
-			info.sessionAffinityType = service.Spec.SessionAffinity
-			glog.V(4).Infof("info: %#v", info)
-
-			err = proxier.openPortal(serviceName, info)
-			if err != nil {
-				glog.Errorf("Failed to open portal for %q: %v", serviceName, err)
-			}
-			proxier.loadBalancer.NewService(serviceName, info.sessionAffinityType, info.stickyMaxAgeMinutes)
+		serviceIP := net.ParseIP(service.Spec.ClusterIP)
+		glog.V(1).Infof("Adding new service %q at %s:%d/%s", serviceName, serviceIP, servicePort.Port, servicePort.Protocol)
+		info, err = proxier.addServiceOnPort(serviceName, servicePort.Protocol, proxyPort, proxier.udpIdleTimeout)
+		if err != nil {
+			glog.Errorf("Failed to start proxy for %q: %v", serviceName, err)
+			continue
 		}
+		info.portal.ip = serviceIP
+		info.portal.port = int(servicePort.Port)
+		info.externalIPs = service.Spec.ExternalIPs
+		// Deep-copy in case the service instance changes
+		info.loadBalancerStatus = *helper.LoadBalancerStatusDeepCopy(&service.Status.LoadBalancer)
+		info.nodePort = int(servicePort.NodePort)
+		info.sessionAffinityType = service.Spec.SessionAffinity
+		glog.V(4).Infof("info: %#v", info)
+
+		if err := proxier.openPortal(serviceName, info); err != nil {
+			glog.Errorf("Failed to open portal for %q: %v", serviceName, err)
+		}
+		proxier.loadBalancer.NewService(serviceName, info.sessionAffinityType, info.stickyMaxAgeMinutes)
+	}
+
+	return existingPorts
+}
+
+func (proxier *Proxier) unmergeService(service *api.Service, existingPorts sets.String) {
+	if service == nil {
+		return
+	}
+	svcName := types.NamespacedName{Namespace: service.Namespace, Name: service.Name}
+	if !helper.IsServiceIPSet(service) {
+		glog.V(3).Infof("Skipping service %s due to clusterIP = %q", svcName, service.Spec.ClusterIP)
+		return
 	}
 
 	staleUDPServices := sets.NewString()
 	proxier.mu.Lock()
 	defer proxier.mu.Unlock()
-	for name, info := range proxier.serviceMap {
-		if !activeServices[name] {
-			glog.V(1).Infof("Stopping service %q", name)
-
-			if proxier.serviceMap[name].protocol == api.ProtocolUDP {
-				staleUDPServices.Insert(proxier.serviceMap[name].portal.ip.String())
-			}
-
-			err := proxier.closePortal(name, info)
-			if err != nil {
-				glog.Errorf("Failed to close portal for %q: %v", name, err)
-			}
-			err = proxier.stopProxyInternal(name, info)
-			if err != nil {
-				glog.Errorf("Failed to stop service %q: %v", name, err)
-			}
-			proxier.loadBalancer.DeleteService(name)
+	for i := range service.Spec.Ports {
+		servicePort := &service.Spec.Ports[i]
+		if existingPorts.Has(servicePort.Name) {
+			continue
 		}
-	}
+		serviceName := proxy.ServicePortName{NamespacedName: svcName, Port: servicePort.Name}
 
+		glog.V(1).Infof("Stopping service %q", serviceName)
+		info, exists := proxier.serviceMap[serviceName]
+		if !exists {
+			glog.Errorf("Service %q is being removed but doesn't exist", serviceName)
+			continue
+		}
+
+		if proxier.serviceMap[serviceName].protocol == api.ProtocolUDP {
+			staleUDPServices.Insert(proxier.serviceMap[serviceName].portal.ip.String())
+		}
+
+		if err := proxier.closePortal(serviceName, info); err != nil {
+			glog.Errorf("Failed to close portal for %q: %v", serviceName, err)
+		}
+		if err := proxier.stopProxyInternal(serviceName, info); err != nil {
+			glog.Errorf("Failed to stop service %q: %v", serviceName, err)
+		}
+		proxier.loadBalancer.DeleteService(serviceName)
+	}
 	utilproxy.DeleteServiceConnections(proxier.exec, staleUDPServices.List())
 }
 
+func (proxier *Proxier) OnServiceAdd(service *api.Service) {
+	_ = proxier.mergeService(service)
+}
+
+func (proxier *Proxier) OnServiceUpdate(oldService, service *api.Service) {
+	existingPorts := proxier.mergeService(service)
+	proxier.unmergeService(oldService, existingPorts)
+}
+
+func (proxier *Proxier) OnServiceDelete(service *api.Service) {
+	proxier.unmergeService(service, sets.NewString())
+}
+
+func (proxier *Proxier) OnServiceSynced() {
+}
+
 func sameConfig(info *ServiceInfo, service *api.Service, port *api.ServicePort) bool {
 	if info.protocol != port.Protocol || info.portal.port != int(port.Port) || info.nodePort != int(port.NodePort) {
 		return false
diff --git a/pkg/proxy/userspace/proxier_test.go b/pkg/proxy/userspace/proxier_test.go
index a3ad8eb0f24..b497318a979 100644
--- a/pkg/proxy/userspace/proxier_test.go
+++ b/pkg/proxy/userspace/proxier_test.go
@@ -326,7 +326,7 @@ func TestMultiPortProxy(t *testing.T) {
 	waitForNumProxyLoops(t, p, 2)
 }
 
-func TestMultiPortOnServiceUpdate(t *testing.T) {
+func TestMultiPortOnServiceAdd(t *testing.T) {
 	lb := NewLoadBalancerRR()
 	serviceP := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: "testnamespace", Name: "echo"}, Port: "p"}
 	serviceQ := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: "testnamespace", Name: "echo"}, Port: "q"}
@@ -340,7 +340,7 @@ func TestMultiPortOnServiceUpdate(t *testing.T) {
 	}
 	waitForNumProxyLoops(t, p, 0)
 
-	p.OnServiceUpdate([]*api.Service{{
+	p.OnServiceAdd(&api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: serviceP.Name, Namespace: serviceP.Namespace},
 		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
 			Name:     "p",
@@ -351,7 +351,7 @@ func TestMultiPortOnServiceUpdate(t *testing.T) {
 			Port:     81,
 			Protocol: "UDP",
 		}}},
-	}})
+	})
 	waitForNumProxyLoops(t, p, 2)
 	svcInfo, exists := p.getServiceInfo(serviceP)
 	if !exists {
@@ -496,7 +496,14 @@ func TestTCPProxyUpdateDelete(t *testing.T) {
 	conn.Close()
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{})
+	p.OnServiceDelete(&api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "TCP",
+		}}},
+	})
 	if err := waitForClosedPortTCP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
 	}
@@ -533,7 +540,14 @@ func TestUDPProxyUpdateDelete(t *testing.T) {
 	conn.Close()
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{})
+	p.OnServiceDelete(&api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "UDP",
+		}}},
+	})
 	if err := waitForClosedPortUDP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
 	}
@@ -571,7 +585,14 @@ func TestTCPProxyUpdateDeleteUpdate(t *testing.T) {
 	conn.Close()
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{})
+	p.OnServiceDelete(&api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "TCP",
+		}}},
+	})
 	if err := waitForClosedPortTCP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
 	}
@@ -579,14 +600,14 @@ func TestTCPProxyUpdateDeleteUpdate(t *testing.T) {
 
 	// need to add endpoint here because it got clean up during service delete
 	lb.OnEndpointsAdd(endpoint)
-	p.OnServiceUpdate([]*api.Service{{
+	p.OnServiceAdd(&api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
 		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
 			Name:     "p",
 			Port:     int32(svcInfo.proxyPort),
 			Protocol: "TCP",
 		}}},
-	}})
+	})
 	svcInfo, exists := p.getServiceInfo(service)
 	if !exists {
 		t.Fatalf("can't find serviceInfo for %s", service)
@@ -626,7 +647,14 @@ func TestUDPProxyUpdateDeleteUpdate(t *testing.T) {
 	conn.Close()
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{})
+	p.OnServiceDelete(&api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "UDP",
+		}}},
+	})
 	if err := waitForClosedPortUDP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
 	}
@@ -634,14 +662,14 @@ func TestUDPProxyUpdateDeleteUpdate(t *testing.T) {
 
 	// need to add endpoint here because it got clean up during service delete
 	lb.OnEndpointsAdd(endpoint)
-	p.OnServiceUpdate([]*api.Service{{
+	p.OnServiceAdd(&api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
 		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
 			Name:     "p",
 			Port:     int32(svcInfo.proxyPort),
 			Protocol: "UDP",
 		}}},
-	}})
+	})
 	svcInfo, exists := p.getServiceInfo(service)
 	if !exists {
 		t.Fatalf("can't find serviceInfo")
@@ -676,14 +704,14 @@ func TestTCPProxyUpdatePort(t *testing.T) {
 	testEchoTCP(t, "127.0.0.1", svcInfo.proxyPort)
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{{
+	p.OnServiceAdd(&api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
 		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
 			Name:     "p",
 			Port:     99,
 			Protocol: "TCP",
 		}}},
-	}})
+	})
 	// Wait for the socket to actually get free.
 	if err := waitForClosedPortTCP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
@@ -723,14 +751,14 @@ func TestUDPProxyUpdatePort(t *testing.T) {
 	}
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{{
+	p.OnServiceAdd(&api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
 		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
 			Name:     "p",
 			Port:     99,
 			Protocol: "UDP",
 		}}},
-	}})
+	})
 	// Wait for the socket to actually get free.
 	if err := waitForClosedPortUDP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
@@ -769,7 +797,7 @@ func TestProxyUpdatePublicIPs(t *testing.T) {
 	testEchoTCP(t, "127.0.0.1", svcInfo.proxyPort)
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{{
+	p.OnServiceAdd(&api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
 		Spec: api.ServiceSpec{
 			Ports: []api.ServicePort{{
@@ -780,7 +808,7 @@ func TestProxyUpdatePublicIPs(t *testing.T) {
 			ClusterIP:   svcInfo.portal.ip.String(),
 			ExternalIPs: []string{"4.3.2.1"},
 		},
-	}})
+	})
 	// Wait for the socket to actually get free.
 	if err := waitForClosedPortTCP(p, svcInfo.proxyPort); err != nil {
 		t.Fatalf(err.Error())
@@ -822,40 +850,52 @@ func TestProxyUpdatePortal(t *testing.T) {
 	testEchoTCP(t, "127.0.0.1", svcInfo.proxyPort)
 	waitForNumProxyLoops(t, p, 1)
 
-	p.OnServiceUpdate([]*api.Service{{
-		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
-		Spec: api.ServiceSpec{ClusterIP: "", Ports: []api.ServicePort{{
-			Name:     "p",
-			Port:     int32(svcInfo.proxyPort),
-			Protocol: "TCP",
-		}}},
-	}})
-	_, exists := p.getServiceInfo(service)
-	if exists {
-		t.Fatalf("service with empty ClusterIP should not be included in the proxy")
-	}
-
-	p.OnServiceUpdate([]*api.Service{{
-		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
-		Spec: api.ServiceSpec{ClusterIP: "None", Ports: []api.ServicePort{{
-			Name:     "p",
-			Port:     int32(svcInfo.proxyPort),
-			Protocol: "TCP",
-		}}},
-	}})
-	_, exists = p.getServiceInfo(service)
-	if exists {
-		t.Fatalf("service with 'None' as ClusterIP should not be included in the proxy")
-	}
-
-	p.OnServiceUpdate([]*api.Service{{
+	svcv0 := &api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
 		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
 			Name:     "p",
 			Port:     int32(svcInfo.proxyPort),
 			Protocol: "TCP",
 		}}},
-	}})
+	}
+
+	svcv1 := &api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "TCP",
+		}}},
+	}
+	p.OnServiceUpdate(svcv0, svcv1)
+	_, exists := p.getServiceInfo(service)
+	if exists {
+		t.Fatalf("service with empty ClusterIP should not be included in the proxy")
+	}
+
+	svcv2 := &api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "None", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "TCP",
+		}}},
+	}
+	p.OnServiceUpdate(svcv1, svcv2)
+	_, exists = p.getServiceInfo(service)
+	if exists {
+		t.Fatalf("service with 'None' as ClusterIP should not be included in the proxy")
+	}
+
+	svcv3 := &api.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: service.Name, Namespace: service.Namespace},
+		Spec: api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{
+			Name:     "p",
+			Port:     int32(svcInfo.proxyPort),
+			Protocol: "TCP",
+		}}},
+	}
+	p.OnServiceUpdate(svcv2, svcv3)
 	lb.OnEndpointsAdd(endpoint)
 	svcInfo, exists = p.getServiceInfo(service)
 	if !exists {