diff --git a/config/notifiers.go b/config/notifiers.go
index e92736a752..96f8e446a6 100644
--- a/config/notifiers.go
+++ b/config/notifiers.go
@@ -18,6 +18,8 @@ import (
 	"net/url"
 	"strings"
 	"time"
+
+	pconfig "github.com/prometheus/common/config"
 )
 
 var (
@@ -297,6 +299,8 @@ type WebhookConfig struct {
 
 	// URL to send POST request to.
 	URL string `yaml:"url" json:"url"`
+	// HTTP client parameters.
+	HTTPClientConfig pconfig.HTTPClientConfig `yaml:"http_client_config,inline" json:"http_client_config,inline"`
 
 	// Catches all undefined fields and must be empty after parsing.
 	XXX map[string]interface{} `yaml:",inline" json:"-"`
diff --git a/notify/impl.go b/notify/impl.go
index 506acdf39a..06c29d7865 100644
--- a/notify/impl.go
+++ b/notify/impl.go
@@ -34,6 +34,7 @@ import (
 
 	"github.com/go-kit/kit/log"
 	"github.com/go-kit/kit/log/level"
+	pconfig "github.com/prometheus/common/config"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/common/version"
 	"golang.org/x/net/context"
@@ -148,13 +149,23 @@ var userAgentHeader = fmt.Sprintf("Alertmanager/%s", version.Version)
 type Webhook struct {
 	// The URL to which notifications are sent.
 	URL    string
+	client *http.Client
 	tmpl   *template.Template
 	logger log.Logger
 }
 
 // NewWebhook returns a new Webhook.
 func NewWebhook(conf *config.WebhookConfig, t *template.Template, l log.Logger) *Webhook {
-	return &Webhook{URL: conf.URL, tmpl: t, logger: l}
+	w := &Webhook{URL: conf.URL, client: http.DefaultClient, tmpl: t, logger: l}
+
+	client, err := pconfig.NewHTTPClientFromConfig(&conf.HTTPClientConfig)
+	if err != nil {
+		level.Error(l).Log("msg", "Failed to create HTTP client for webhook", "err", err, "url", conf.URL)
+	} else {
+		w.client = client
+	}
+
+	return w
 }
 
 // WebhookMessage defines the JSON object send to webhook endpoints.
@@ -193,7 +204,7 @@ func (w *Webhook) Notify(ctx context.Context, alerts ...*types.Alert) (bool, err
 	req.Header.Set("Content-Type", contentTypeJSON)
 	req.Header.Set("User-Agent", userAgentHeader)
 
-	resp, err := ctxhttp.Do(ctx, http.DefaultClient, req)
+	resp, err := ctxhttp.Do(ctx, w.client, req)
 	if err != nil {
 		return true, err
 	}
diff --git a/vendor/github.com/prometheus/common/config/config.go b/vendor/github.com/prometheus/common/config/config.go
new file mode 100644
index 0000000000..9195c34bfd
--- /dev/null
+++ b/vendor/github.com/prometheus/common/config/config.go
@@ -0,0 +1,47 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"fmt"
+	"strings"
+)
+
+func checkOverflow(m map[string]interface{}, ctx string) error {
+	if len(m) > 0 {
+		var keys []string
+		for k := range m {
+			keys = append(keys, k)
+		}
+		return fmt.Errorf("unknown fields in %s: %s", ctx, strings.Join(keys, ", "))
+	}
+	return nil
+}
+
+// Secret special type for storing secrets.
+type Secret string
+
+// MarshalYAML implements the yaml.Marshaler interface for Secrets.
+func (s Secret) MarshalYAML() (interface{}, error) {
+	if s != "" {
+		return "<secret>", nil
+	}
+	return nil, nil
+}
+
+//UnmarshalYAML implements the yaml.Unmarshaler interface for Secrets.
+func (s *Secret) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type plain Secret
+	return unmarshal((*plain)(s))
+}
diff --git a/vendor/github.com/prometheus/common/config/http_config.go b/vendor/github.com/prometheus/common/config/http_config.go
new file mode 100644
index 0000000000..ff5837fa5e
--- /dev/null
+++ b/vendor/github.com/prometheus/common/config/http_config.go
@@ -0,0 +1,279 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+// BasicAuth contains basic HTTP authentication credentials.
+type BasicAuth struct {
+	Username string `yaml:"username"`
+	Password Secret `yaml:"password"`
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline"`
+}
+
+// URL is a custom URL type that allows validation at configuration load time.
+type URL struct {
+	*url.URL
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface for URLs.
+func (u *URL) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+
+	urlp, err := url.Parse(s)
+	if err != nil {
+		return err
+	}
+	u.URL = urlp
+	return nil
+}
+
+// MarshalYAML implements the yaml.Marshaler interface for URLs.
+func (u URL) MarshalYAML() (interface{}, error) {
+	if u.URL != nil {
+		return u.String(), nil
+	}
+	return nil, nil
+}
+
+// HTTPClientConfig configures an HTTP client.
+type HTTPClientConfig struct {
+	// The HTTP basic authentication credentials for the targets.
+	BasicAuth *BasicAuth `yaml:"basic_auth,omitempty"`
+	// The bearer token for the targets.
+	BearerToken Secret `yaml:"bearer_token,omitempty"`
+	// The bearer token file for the targets.
+	BearerTokenFile string `yaml:"bearer_token_file,omitempty"`
+	// HTTP proxy server to use to connect to the targets.
+	ProxyURL URL `yaml:"proxy_url,omitempty"`
+	// TLSConfig to use to connect to the targets.
+	TLSConfig TLSConfig `yaml:"tls_config,omitempty"`
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline"`
+}
+
+func (c *HTTPClientConfig) validate() error {
+	if len(c.BearerToken) > 0 && len(c.BearerTokenFile) > 0 {
+		return fmt.Errorf("at most one of bearer_token & bearer_token_file must be configured")
+	}
+	if c.BasicAuth != nil && (len(c.BearerToken) > 0 || len(c.BearerTokenFile) > 0) {
+		return fmt.Errorf("at most one of basic_auth, bearer_token & bearer_token_file must be configured")
+	}
+	return nil
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface
+func (c *HTTPClientConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type plain HTTPClientConfig
+	err := unmarshal((*plain)(c))
+	if err != nil {
+		return err
+	}
+	err = c.validate()
+	if err != nil {
+		return c.validate()
+	}
+	return checkOverflow(c.XXX, "http_client_config")
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (a *BasicAuth) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type plain BasicAuth
+	err := unmarshal((*plain)(a))
+	if err != nil {
+		return err
+	}
+	return checkOverflow(a.XXX, "basic_auth")
+}
+
+// NewHTTPClientFromConfig returns a new HTTP client configured for the
+// given config.HTTPClientConfig.
+func NewHTTPClientFromConfig(cfg *HTTPClientConfig) (*http.Client, error) {
+	tlsConfig, err := NewTLSConfig(&cfg.TLSConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	// It's the caller's job to handle timeouts
+	var rt http.RoundTripper = &http.Transport{
+		Proxy:             http.ProxyURL(cfg.ProxyURL.URL),
+		DisableKeepAlives: true,
+		TLSClientConfig:   tlsConfig,
+	}
+
+	// If a bearer token is provided, create a round tripper that will set the
+	// Authorization header correctly on each request.
+	bearerToken := cfg.BearerToken
+	if len(bearerToken) == 0 && len(cfg.BearerTokenFile) > 0 {
+		b, err := ioutil.ReadFile(cfg.BearerTokenFile)
+		if err != nil {
+			return nil, fmt.Errorf("unable to read bearer token file %s: %s", cfg.BearerTokenFile, err)
+		}
+		bearerToken = Secret(strings.TrimSpace(string(b)))
+	}
+
+	if len(bearerToken) > 0 {
+		rt = NewBearerAuthRoundTripper(bearerToken, rt)
+	}
+
+	if cfg.BasicAuth != nil {
+		rt = NewBasicAuthRoundTripper(cfg.BasicAuth.Username, Secret(cfg.BasicAuth.Password), rt)
+	}
+
+	// Return a new client with the configured round tripper.
+	return &http.Client{Transport: rt}, nil
+}
+
+type bearerAuthRoundTripper struct {
+	bearerToken Secret
+	rt          http.RoundTripper
+}
+
+type basicAuthRoundTripper struct {
+	username string
+	password Secret
+	rt       http.RoundTripper
+}
+
+// NewBasicAuthRoundTripper will apply a BASIC auth authorization header to a request unless it has
+// already been set.
+func NewBasicAuthRoundTripper(username string, password Secret, rt http.RoundTripper) http.RoundTripper {
+	return &basicAuthRoundTripper{username, password, rt}
+}
+
+func (rt *bearerAuthRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	if len(req.Header.Get("Authorization")) == 0 {
+		req = cloneRequest(req)
+		req.Header.Set("Authorization", "Bearer "+string(rt.bearerToken))
+	}
+
+	return rt.rt.RoundTrip(req)
+}
+
+// NewBearerAuthRoundTripper adds the provided bearer token to a request unless the authorization
+// header has already been set.
+func NewBearerAuthRoundTripper(bearer Secret, rt http.RoundTripper) http.RoundTripper {
+	return &bearerAuthRoundTripper{bearer, rt}
+}
+
+func (rt *basicAuthRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	if len(req.Header.Get("Authorization")) != 0 {
+		return rt.RoundTrip(req)
+	}
+	req = cloneRequest(req)
+	req.SetBasicAuth(rt.username, string(rt.password))
+	return rt.rt.RoundTrip(req)
+}
+
+// cloneRequest returns a clone of the provided *http.Request.
+// The clone is a shallow copy of the struct and its Header map.
+func cloneRequest(r *http.Request) *http.Request {
+	// Shallow copy of the struct.
+	r2 := new(http.Request)
+	*r2 = *r
+	// Deep copy of the Header.
+	r2.Header = make(http.Header)
+	for k, s := range r.Header {
+		r2.Header[k] = s
+	}
+	return r2
+}
+
+// NewTLSConfig creates a new tls.Config from the given config.TLSConfig.
+func NewTLSConfig(cfg *TLSConfig) (*tls.Config, error) {
+	tlsConfig := &tls.Config{InsecureSkipVerify: cfg.InsecureSkipVerify}
+
+	// If a CA cert is provided then let's read it in so we can validate the
+	// scrape target's certificate properly.
+	if len(cfg.CAFile) > 0 {
+		caCertPool := x509.NewCertPool()
+		// Load CA cert.
+		caCert, err := ioutil.ReadFile(cfg.CAFile)
+		if err != nil {
+			return nil, fmt.Errorf("unable to use specified CA cert %s: %s", cfg.CAFile, err)
+		}
+		caCertPool.AppendCertsFromPEM(caCert)
+		tlsConfig.RootCAs = caCertPool
+	}
+
+	if len(cfg.ServerName) > 0 {
+		tlsConfig.ServerName = cfg.ServerName
+	}
+
+	// If a client cert & key is provided then configure TLS config accordingly.
+	if len(cfg.CertFile) > 0 && len(cfg.KeyFile) == 0 {
+		return nil, fmt.Errorf("client cert file %q specified without client key file", cfg.CertFile)
+	} else if len(cfg.KeyFile) > 0 && len(cfg.CertFile) == 0 {
+		return nil, fmt.Errorf("client key file %q specified without client cert file", cfg.KeyFile)
+	} else if len(cfg.CertFile) > 0 && len(cfg.KeyFile) > 0 {
+		cert, err := tls.LoadX509KeyPair(cfg.CertFile, cfg.KeyFile)
+		if err != nil {
+			return nil, fmt.Errorf("unable to use specified client cert (%s) & key (%s): %s", cfg.CertFile, cfg.KeyFile, err)
+		}
+		tlsConfig.Certificates = []tls.Certificate{cert}
+	}
+	tlsConfig.BuildNameToCertificate()
+
+	return tlsConfig, nil
+}
+
+// TLSConfig configures the options for TLS connections.
+type TLSConfig struct {
+	// The CA cert to use for the targets.
+	CAFile string `yaml:"ca_file,omitempty"`
+	// The client cert file for the targets.
+	CertFile string `yaml:"cert_file,omitempty"`
+	// The client key file for the targets.
+	KeyFile string `yaml:"key_file,omitempty"`
+	// Used to verify the hostname for the targets.
+	ServerName string `yaml:"server_name,omitempty"`
+	// Disable target certificate validation.
+	InsecureSkipVerify bool `yaml:"insecure_skip_verify"`
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline"`
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (c *TLSConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type plain TLSConfig
+	if err := unmarshal((*plain)(c)); err != nil {
+		return err
+	}
+	return checkOverflow(c.XXX, "TLS config")
+}
+
+func (c HTTPClientConfig) String() string {
+	b, err := yaml.Marshal(c)
+	if err != nil {
+		return fmt.Sprintf("<error creating http client config string: %s>", err)
+	}
+	return string(b)
+}
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 53ebded71f..91b4a01fe0 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -250,6 +250,12 @@
 			"revision": "1e01b2bdbae8edb393fcf555732304f34d192fc9",
 			"revisionTime": "2016-11-21T14:22:35Z"
 		},
+		{
+			"checksumSHA1": "4TLgSCgJZuS5gtytxNvcVk4h8/g=",
+			"path": "github.com/prometheus/common/config",
+			"revision": "2e54d0b93cba2fd133edc32211dcc32c06ef72ca",
+			"revisionTime": "2017-11-17T16:30:51Z"
+		},
 		{
 			"checksumSHA1": "xfnn0THnqNwjwimeTClsxahYrIo=",
 			"path": "github.com/prometheus/common/expfmt",