diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8a626c5e..aa6b45a6 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -99,6 +99,17 @@ jobs:
     - store_test_results:
         path: test-results
 
+  mixin:
+    docker:
+    # Whenever the Go version is updated here, .promu.yml should also be updated.
+    - image: circleci/golang:1.14
+
+    steps:
+    - checkout
+    - run: cd doc/alertmanager-mixin; go install github.com/monitoring-mixins/mixtool/cmd/mixtool
+    - run: cd doc/alertmanager-mixin; go install github.com/google/go-jsonnet/cmd/jsonnetfmt
+    - run: cd doc/alertmanager-mixin; make lint
+
 workflows:
   version: 2
   alertmanager:
@@ -116,6 +127,10 @@ workflows:
         filters:
           tags:
             only: /.*/
+    - mixin:
+        filters:
+          tags:
+            only: /.*/
     - prometheus/publish_master:
         context: org-context
         requires:
diff --git a/doc/alertmanager-mixin/Makefile b/doc/alertmanager-mixin/Makefile
new file mode 100644
index 00000000..360ddf2d
--- /dev/null
+++ b/doc/alertmanager-mixin/Makefile
@@ -0,0 +1,24 @@
+JSONNET_FMT := jsonnetfmt -n 2 --max-blank-lines 2 --string-style s --comment-style s
+ALERTMANAGER_ALERTS := alertmanager_alerts.yaml
+
+default: build
+
+all: fmt build
+
+fmt:
+	find . -name 'vendor' -prune -o -name '*.libsonnet' -print -o -name '*.jsonnet' -print | \
+		xargs -n 1 -- $(JSONNET_FMT) -i
+
+lint: build
+	find . -name 'vendor' -prune -o -name '*.libsonnet' -print -o -name '*.jsonnet' -print | \
+		while read f; do \
+			$(JSONNET_FMT) "$$f" | diff -u "$$f" -; \
+		done
+
+	mixtool lint mixin.libsonnet
+
+build:
+	mixtool generate alerts mixin.libsonnet > $(ALERTMANAGER_ALERTS)
+
+clean:
+	rm -rf $(ALERTMANAGER_ALERTS)
diff --git a/doc/alertmanager-mixin/README.md b/doc/alertmanager-mixin/README.md
new file mode 100644
index 00000000..d3190d75
--- /dev/null
+++ b/doc/alertmanager-mixin/README.md
@@ -0,0 +1,30 @@
+# Alertmanager Mixin
+
+The Alertmanager Mixin is a set of configurable, reusable, and extensible
+alerts (and eventually dashboards) for Alertmanager.
+
+The alerts are designed to monitor a cluster of Alertmanager instances. To make
+them work as expected, the Prometheus server the alerts are evaluated on has to
+scrape all Alertmanager instances of the cluster, even if those instances are
+distributed over different locations. All Alertmanager instances in the same
+Alertmanager cluster must have the same `job` label. In turn, if monitoring
+multiple different Alertmanager clusters, instances from different clusters
+must have a different `job` label.
+
+The most basic use of the Alertmanager Mixin is to create a YAML file with the
+alerts from it. To do so, you need to have `jsonnetfmt` and `mixtool` installed. If you have a working Go development environment, it's
+easiest to run the following:
+
+```bash
+$ go get github.com/monitoring-mixins/mixtool/cmd/mixtool
+$ go get github.com/google/go-jsonnet/cmd/jsonnetfmt
+```
+
+Edit `config.libsonnet` to match your environment and then build
+`alertmanager_alerts.yaml` with the alerts by running:
+
+```bash
+$ make build
+```
+
+For instructions on more advanced uses of mixins, see https://github.com/monitoring-mixins/docs.
diff --git a/doc/alertmanager-mixin/alerts.jsonnet b/doc/alertmanager-mixin/alerts.jsonnet
new file mode 100644
index 00000000..75e7c1b2
--- /dev/null
+++ b/doc/alertmanager-mixin/alerts.jsonnet
@@ -0,0 +1 @@
+std.manifestYamlDoc((import 'mixin.libsonnet').prometheusAlerts)
diff --git a/doc/alertmanager-mixin/alerts.libsonnet b/doc/alertmanager-mixin/alerts.libsonnet
new file mode 100644
index 00000000..eb57ace4
--- /dev/null
+++ b/doc/alertmanager-mixin/alerts.libsonnet
@@ -0,0 +1,150 @@
+{
+  prometheusAlerts+:: {
+    groups+: [
+      {
+        name: 'alertmanager.rules',
+        rules: [
+          {
+            alert: 'AlertmanagerFailedReload',
+            expr: |||
+              # Without max_over_time, failed scrapes could create false negatives, see
+              # https://www.robustperception.io/alerting-on-gauges-in-prometheus-2-0 for details.
+              max_over_time(alertmanager_config_last_reload_successful{%(alertmanagerSelector)s}[5m]) == 0
+            ||| % $._config,
+            'for': '10m',
+            labels: {
+              severity: 'critical',
+            },
+            annotations: {
+              summary: 'Reloading an Alertmanager configuration has failed.',
+              description: 'Configuration has failed to load for %(alertmanagerName)s.' % $._config,
+            },
+          },
+          {
+            alert: 'AlertmanagerMembersInconsistent',
+            expr: |||
+              # Without max_over_time, failed scrapes could create false negatives, see
+              # https://www.robustperception.io/alerting-on-gauges-in-prometheus-2-0 for details.
+                max_over_time(alertmanager_cluster_members{%(alertmanagerSelector)s}[5m])
+              < on (%(alertmanagerClusterLabels)s) group_left
+                count by (%(alertmanagerClusterLabels)s) (max_over_time(alertmanager_cluster_members{%(alertmanagerSelector)s}[5m]))
+            ||| % $._config,
+            'for': '10m',
+            labels: {
+              severity: 'critical',
+            },
+            annotations: {
+              summary: 'A member of an Alertmanager cluster has not found all other cluster members.',
+              description: 'Alertmanager %(alertmanagerName)s has only found {{ $value }} members of the %(alertmanagerClusterName)s cluster.' % $._config,
+            },
+          },
+          {
+            alert: 'AlertmanagerFailedToSendAlerts',
+            expr: |||
+              (
+                rate(alertmanager_notifications_failed_total{%(alertmanagerSelector)s}[5m])
+              /
+                rate(alertmanager_notifications_total{%(alertmanagerSelector)s}[5m])
+              )
+              > 0.01
+            ||| % $._config,
+            'for': '5m',
+            labels: {
+              severity: 'warning',
+            },
+            annotations: {
+              summary: 'An Alertmanager instance failed to send notifications.',
+              description: 'Alertmanager %(alertmanagerName)s failed to send {{ $value | humanizePercentage }} of notifications to {{ $labels.integration }}.' % $._config,
+            },
+          },
+          {
+            alert: 'AlertmanagerClusterFailedToSendAlerts',
+            expr: |||
+              min by (%(alertmanagerClusterLabels)s) (
+                rate(alertmanager_notifications_failed_total{%(alertmanagerSelector)s}[5m])
+              /
+                rate(alertmanager_notifications_total{%(alertmanagerSelector)s}[5m])
+              )
+              > 0.01
+            ||| % $._config,
+            'for': '5m',
+            labels: {
+              severity: 'critical',
+            },
+            annotations: {
+              summary: 'All Alertmanager instances in a cluster failed to send notifications.',
+              description: 'The minimum notification failure rate to {{ $labels.integration }} sent from any instance in the %(alertmanagerClusterName)s cluster is {{ $value | humanizePercentage }}.' % $._config,
+            },
+          },
+          {
+            alert: 'AlertmanagerConfigInconsistent',
+            expr: |||
+              count by (%(alertmanagerClusterLabels)s) (
+                count_values by (%(alertmanagerClusterLabels)s) ("config_hash", alertmanager_config_hash{%(alertmanagerSelector)s})
+              )
+              != 1
+            ||| % $._config,
+            'for': '20m',  // A config change across an Alertmanager cluster can take its time. But it's really bad if it persists for too long.
+            labels: {
+              severity: 'critical',
+            },
+            annotations: {
+              summary: 'Alertmanager instances within the same cluster have different configurations.',
+              description: 'Alertmanager instances within the %(alertmanagerClusterName)s cluster have different configurations.' % $._config,
+            },
+          },
+          // Both the following critical alerts, AlertmanagerClusterDown and
+          // AlertmanagerClusterCrashlooping, fire if a whole cluster is
+          // unhealthy. It is implied that a generic warning alert is in place
+          // for individual instances being down or crashlooping.
+          {
+            alert: 'AlertmanagerClusterDown',
+            expr: |||
+              (
+                count by (%(alertmanagerClusterLabels)s) (
+                  avg_over_time(up{%(alertmanagerSelector)s}[5m]) < 0.5
+                )
+              /
+                count by (%(alertmanagerClusterLabels)s) (
+                  up{%(alertmanagerSelector)s}
+                )
+              )
+              >= 0.5
+            ||| % $._config,
+            'for': '5m',
+            labels: {
+              severity: 'critical',
+            },
+            annotations: {
+              summary: 'Half or more of the Alertmanager instances within the same cluster are down.',
+              description: '{{ $value | humanizePercentage }} of Alertmanager instances within the %(alertmanagerClusterName)s cluster have been up for less than half of the last 5m.' % $._config,
+            },
+          },
+          {
+            alert: 'AlertmanagerClusterCrashlooping',
+            expr: |||
+              (
+                count by (%(alertmanagerClusterLabels)s) (
+                  changes(process_start_time_seconds{%(alertmanagerSelector)s}[10m]) > 4
+                )
+              /
+                count by (%(alertmanagerClusterLabels)s) (
+                  up{%(alertmanagerSelector)s}
+                )
+              )
+              >= 0.5
+            ||| % $._config,
+            'for': '5m',
+            labels: {
+              severity: 'critical',
+            },
+            annotations: {
+              summary: 'Half or more of the Alertmanager instances within the same cluster are crashlooping.',
+              description: '{{ $value | humanizePercentage }} of Alertmanager instances within the %(alertmanagerClusterName)s cluster have restarted at least 5 times in the last 10m.' % $._config,
+            },
+          },
+        ],
+      },
+    ],
+  },
+}
diff --git a/doc/alertmanager-mixin/config.libsonnet b/doc/alertmanager-mixin/config.libsonnet
new file mode 100644
index 00000000..001886ca
--- /dev/null
+++ b/doc/alertmanager-mixin/config.libsonnet
@@ -0,0 +1,28 @@
+{
+  _config+:: {
+    // alertmanagerSelector is inserted as part of the label selector in
+    // PromQL queries to identify metrics collected from Alertmanager
+    // servers.
+    alertmanagerSelector: 'job="alertmanager"',
+
+    // alertmanagerClusterLabels is a string with comma-separated
+    // labels that are common labels of instances belonging to the
+    // same Alertmanager cluster. Include not only enough labels to
+    // identify cluster members, but also all common labels you want
+    // to keep for resulting cluster-level alerts.
+    alertmanagerClusterLabels: 'job',
+
+    // alertmanagerName is inserted into annotations to name the Alertmanager
+    // instance affected by the alert.
+    alertmanagerName: '{{$labels.instance}}',
+    // If you run Alertmanager on Kubernetes with the Prometheus
+    // Operator, you can make use of the configured target labels for
+    // nicer naming:
+    // alertmanagerName: '{{$labels.namespace}}/{{$labels.pod}}'
+
+    // alertmanagerClusterName is inserted into annotations to name an
+    // Alertmanager cluster. All labels used here must also be present
+    // in alertmanagerClusterLabels above.
+    alertmanagerClusterName: '{{$labels.job}}',
+  },
+}
diff --git a/doc/alertmanager-mixin/go.mod b/doc/alertmanager-mixin/go.mod
new file mode 100644
index 00000000..e4d814ac
--- /dev/null
+++ b/doc/alertmanager-mixin/go.mod
@@ -0,0 +1,8 @@
+module github.com/prometheus/alertmanager/doc/alertmanager-mixin
+
+go 1.14
+
+require (
+	github.com/google/go-jsonnet v0.17.0 // indirect
+	github.com/monitoring-mixins/mixtool v0.0.0-20201127170310-63dca667103c // indirect
+)
diff --git a/doc/alertmanager-mixin/mixin.libsonnet b/doc/alertmanager-mixin/mixin.libsonnet
new file mode 100644
index 00000000..95efe331
--- /dev/null
+++ b/doc/alertmanager-mixin/mixin.libsonnet
@@ -0,0 +1,2 @@
+(import 'config.libsonnet') +
+(import 'alerts.libsonnet')