diff --git a/Gemfile b/Gemfile
index 95cb04f0a8d..6fb5ac813ca 100644
--- a/Gemfile
+++ b/Gemfile
@@ -126,6 +126,9 @@ group :production do
   # requires memcached 1.4+
   # see https://github.clientom/mperham/dalli
   gem 'dalli', '~> 2.7.6'
+
+  # Unicorn worker killer to restart unicorn child workers
+  gem 'unicorn-worker-killer', require: false
 end
 
 gem 'sprockets', '~> 3.7.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index d57ba26ba21..ef7812c928a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -288,6 +288,7 @@ GEM
     fuubar (2.2.0)
       rspec-core (~> 3.0)
       ruby-progressbar (~> 1.4)
+    get_process_mem (0.2.1)
     gherkin (4.0.0)
     globalid (0.3.7)
       activesupport (>= 4.1.0)
@@ -560,6 +561,9 @@ GEM
     unicorn (5.1.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
+    unicorn-worker-killer (0.4.4)
+      get_process_mem (~> 0)
+      unicorn (>= 4, < 6)
     url (0.3.2)
     virtus (1.0.5)
       axiom-types (~> 0.1)
@@ -698,6 +702,7 @@ DEPENDENCIES
   transactional_lock!
   tzinfo-data (~> 1.2016.1)
   unicorn
+  unicorn-worker-killer
   warden (~> 1.2)
   warden-basic_auth (~> 0.2.1)
   webmock (~> 2.1.0)
diff --git a/config.ru b/config.ru
index 6c313e9fa62..5797be10d1e 100644
--- a/config.ru
+++ b/config.ru
@@ -31,6 +31,23 @@
 
 require ::File.expand_path('../config/environment',  __FILE__)
 
+##
+# Use the worker killer when Unicorn is being used
+if defined?(Unicorn) && Rails.env.production?
+  require 'unicorn/worker_killer'
+
+  min_ram = ENV.fetch('OPENPROJECT_UNICORN_RAM2KILL_MIN', 340 * 1 << 20).to_i
+  max_ram = ENV.fetch('OPENPROJECT_UNICORN_RAM2KILL_MAX', 400 * 1 << 20).to_i
+  min_req = ENV.fetch('OPENPROJECT_UNICORN_REQ2KILL_MIN', 3072).to_i
+  max_req = ENV.fetch('OPENPROJECT_UNICORN_REQ2KILL_MAX', 4096).to_i
+
+  # Kill Workers randomly between 340 and 400 MB (per default)
+  # or between 3072 and 4096 requests.
+  # Our largest installations are starting around 200/230 MB
+  use Unicorn::WorkerKiller::Oom, min_ram, max_ram
+  use Unicorn::WorkerKiller::MaxRequests, min_req, max_req
+end
+
 ##
 # Returns true if the application should be run under a subdirectory.
 def map_subdir?