diff --git a/template/template.go b/template/template.go
index 961ad746..2f4e1ee3 100644
--- a/template/template.go
+++ b/template/template.go
@@ -15,16 +15,15 @@ package template
 
 import (
 	"bytes"
+	tmplhtml "html/template"
 	"io/ioutil"
 	"net/url"
 	"path/filepath"
 	"regexp"
 	"sort"
 	"strings"
-	"time"
-
-	tmplhtml "html/template"
 	tmpltext "text/template"
+	"time"
 
 	"github.com/prometheus/common/model"
 
@@ -315,6 +314,9 @@ func (t *Template) Data(recv string, groupLabels model.LabelSet, alerts ...*type
 			commonAnnotations = alerts[0].Annotations.Clone()
 		)
 		for _, a := range alerts[1:] {
+			if len(commonLabels) == 0 && len(commonAnnotations) == 0 {
+				break
+			}
 			for ln, lv := range commonLabels {
 				if a.Labels[ln] != lv {
 					delete(commonLabels, ln)
diff --git a/template/template_test.go b/template/template_test.go
index 152e1bf6..7b503040 100644
--- a/template/template_test.go
+++ b/template/template_test.go
@@ -14,10 +14,14 @@
 package template
 
 import (
+	"net/url"
 	"testing"
+	"time"
 
 	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
+
+	"github.com/prometheus/alertmanager/types"
 )
 
 func TestPairNames(t *testing.T) {
@@ -118,3 +122,251 @@ func TestAlertsResolved(t *testing.T) {
 		}
 	}
 }
+
+func TestData(t *testing.T) {
+	u, err := url.Parse("http://example.com/")
+	require.NoError(t, err)
+	tmpl := &Template{ExternalURL: u}
+	startTime := time.Time{}.Add(1 * time.Second)
+	endTime := time.Time{}.Add(2 * time.Second)
+
+	for _, tc := range []struct {
+		receiver    string
+		groupLabels model.LabelSet
+		alerts      []*types.Alert
+
+		exp *Data
+	}{
+		{
+			receiver: "webhook",
+			exp: &Data{
+				Receiver:          "webhook",
+				Status:            "resolved",
+				Alerts:            Alerts{},
+				GroupLabels:       KV{},
+				CommonLabels:      KV{},
+				CommonAnnotations: KV{},
+				ExternalURL:       u.String(),
+			},
+		},
+		{
+			receiver: "webhook",
+			groupLabels: model.LabelSet{
+				model.LabelName("job"): model.LabelValue("foo"),
+			},
+			alerts: []*types.Alert{
+				{
+					Alert: model.Alert{
+						StartsAt: startTime,
+						Labels: model.LabelSet{
+							model.LabelName("severity"): model.LabelValue("warning"),
+							model.LabelName("job"):      model.LabelValue("foo"),
+						},
+						Annotations: model.LabelSet{
+							model.LabelName("description"): model.LabelValue("something happened"),
+							model.LabelName("runbook"):     model.LabelValue("foo"),
+						},
+					},
+				},
+				{
+					Alert: model.Alert{
+						StartsAt: startTime,
+						EndsAt:   endTime,
+						Labels: model.LabelSet{
+							model.LabelName("severity"): model.LabelValue("critical"),
+							model.LabelName("job"):      model.LabelValue("foo"),
+						},
+						Annotations: model.LabelSet{
+							model.LabelName("description"): model.LabelValue("something else happened"),
+							model.LabelName("runbook"):     model.LabelValue("foo"),
+						},
+					},
+				},
+			},
+			exp: &Data{
+				Receiver: "webhook",
+				Status:   "firing",
+				Alerts: Alerts{
+					{
+						Status:      "firing",
+						Labels:      KV{"severity": "warning", "job": "foo"},
+						Annotations: KV{"description": "something happened", "runbook": "foo"},
+						StartsAt:    startTime,
+					},
+					{
+						Status:      "resolved",
+						Labels:      KV{"severity": "critical", "job": "foo"},
+						Annotations: KV{"description": "something else happened", "runbook": "foo"},
+						StartsAt:    startTime,
+						EndsAt:      endTime,
+					},
+				},
+				GroupLabels:       KV{"job": "foo"},
+				CommonLabels:      KV{"job": "foo"},
+				CommonAnnotations: KV{"runbook": "foo"},
+				ExternalURL:       u.String(),
+			},
+		},
+		{
+			receiver:    "webhook",
+			groupLabels: model.LabelSet{},
+			alerts: []*types.Alert{
+				{
+					Alert: model.Alert{
+						StartsAt: startTime,
+						Labels: model.LabelSet{
+							model.LabelName("severity"): model.LabelValue("warning"),
+							model.LabelName("job"):      model.LabelValue("foo"),
+						},
+						Annotations: model.LabelSet{
+							model.LabelName("description"): model.LabelValue("something happened"),
+							model.LabelName("runbook"):     model.LabelValue("foo"),
+						},
+					},
+				},
+				{
+					Alert: model.Alert{
+						StartsAt: startTime,
+						EndsAt:   endTime,
+						Labels: model.LabelSet{
+							model.LabelName("severity"): model.LabelValue("critical"),
+							model.LabelName("job"):      model.LabelValue("bar"),
+						},
+						Annotations: model.LabelSet{
+							model.LabelName("description"): model.LabelValue("something else happened"),
+							model.LabelName("runbook"):     model.LabelValue("bar"),
+						},
+					},
+				},
+			},
+			exp: &Data{
+				Receiver: "webhook",
+				Status:   "firing",
+				Alerts: Alerts{
+					{
+						Status:      "firing",
+						Labels:      KV{"severity": "warning", "job": "foo"},
+						Annotations: KV{"description": "something happened", "runbook": "foo"},
+						StartsAt:    startTime,
+					},
+					{
+						Status:      "resolved",
+						Labels:      KV{"severity": "critical", "job": "bar"},
+						Annotations: KV{"description": "something else happened", "runbook": "bar"},
+						StartsAt:    startTime,
+						EndsAt:      endTime,
+					},
+				},
+				GroupLabels:       KV{},
+				CommonLabels:      KV{},
+				CommonAnnotations: KV{},
+				ExternalURL:       u.String(),
+			},
+		},
+	} {
+		tc := tc
+		t.Run("", func(t *testing.T) {
+			got := tmpl.Data(tc.receiver, tc.groupLabels, tc.alerts...)
+			require.Equal(t, tc.exp, got)
+		})
+	}
+}
+
+func TestTemplateExpansion(t *testing.T) {
+	tmpl, err := FromGlobs()
+	require.NoError(t, err)
+
+	for _, tc := range []struct {
+		title string
+		in    string
+		data  interface{}
+		html  bool
+
+		exp  string
+		fail bool
+	}{
+		{
+			title: "Template without action",
+			in:    `abc`,
+			exp:   "abc",
+		},
+		{
+			title: "Template with simple action",
+			in:    `{{ "abc" }}`,
+			exp:   "abc",
+		},
+		{
+			title: "Template with invalid syntax",
+			in:    `{{ `,
+			fail:  true,
+		},
+		{
+			title: "Template using toUpper",
+			in:    `{{ "abc" | toUpper }}`,
+			exp:   "ABC",
+		},
+		{
+			title: "Template using toLower",
+			in:    `{{ "ABC" | toLower }}`,
+			exp:   "abc",
+		},
+		{
+			title: "Template using title",
+			in:    `{{ "abc" | title }}`,
+			exp:   "Abc",
+		},
+		{
+			title: "Template using positive match",
+			in:    `{{ if match "^a" "abc"}}abc{{ end }}`,
+			exp:   "abc",
+		},
+		{
+			title: "Template using negative match",
+			in:    `{{ if match "abcd" "abc" }}abc{{ end }}`,
+			exp:   "",
+		},
+		{
+			title: "Template using join",
+			in:    `{{ . | join "," }}`,
+			data:  []string{"a", "b", "c"},
+			exp:   "a,b,c",
+		},
+		{
+			title: "Text template without HTML escaping",
+			in:    `{{ "<b>" }}`,
+			exp:   "<b>",
+		},
+		{
+			title: "HTML template with escaping",
+			in:    `{{ "<b>" }}`,
+			html:  true,
+			exp:   "&lt;b&gt;",
+		},
+		{
+			title: "HTML template using safeHTML",
+			in:    `{{ "<b>" | safeHtml }}`,
+			html:  true,
+			exp:   "<b>",
+		},
+		{
+			title: "Template using reReplaceAll",
+			in:    `{{ reReplaceAll "ab" "AB" "abcdabcda"}}`,
+			exp:   "ABcdABcda",
+		},
+	} {
+		tc := tc
+		t.Run(tc.title, func(t *testing.T) {
+			f := tmpl.ExecuteTextString
+			if tc.html {
+				f = tmpl.ExecuteHTMLString
+			}
+			got, err := f(tc.in, tc.data)
+			if tc.fail {
+				require.NotNil(t, err)
+				return
+			}
+			require.NoError(t, err)
+			require.Equal(t, tc.exp, got)
+		})
+	}
+}