diff --git a/dom/serviceworkers/ServiceWorkerPrivate.cpp b/dom/serviceworkers/ServiceWorkerPrivate.cpp
index 904494b6895e..d10a7ddb4a15 100644
--- a/dom/serviceworkers/ServiceWorkerPrivate.cpp
+++ b/dom/serviceworkers/ServiceWorkerPrivate.cpp
@@ -1947,7 +1947,7 @@ void
 ServiceWorkerPrivate::StoreISupports(nsISupports* aSupports)
 {
   MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(mWorkerPrivate);
+  MOZ_DIAGNOSTIC_ASSERT(mWorkerPrivate);
   MOZ_ASSERT(!mSupportsArray.Contains(aSupports));
 
   mSupportsArray.AppendElement(aSupports);
diff --git a/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp b/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp
index 3c25768fd793..81f7b6e55539 100644
--- a/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp
+++ b/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp
@@ -25,6 +25,7 @@
 #include "nsServiceManagerUtils.h"
 #include "ServiceWorker.h"
 #include "ServiceWorkerManager.h"
+#include "ServiceWorkerPrivate.h"
 #include "ServiceWorkerRegistration.h"
 
 #include "nsIDocument.h"
@@ -133,7 +134,7 @@ namespace {
 
 void
 UpdateInternal(nsIPrincipal* aPrincipal,
-               const nsAString& aScope,
+               const nsACString& aScope,
                ServiceWorkerUpdateFinishCallback* aCallback)
 {
   MOZ_ASSERT(NS_IsMainThread());
@@ -146,7 +147,7 @@ UpdateInternal(nsIPrincipal* aPrincipal,
     return;
   }
 
-  swm->Update(aPrincipal, NS_ConvertUTF16toUTF8(aScope), aCallback);
+  swm->Update(aPrincipal, aScope, aCallback);
 }
 
 class MainThreadUpdateCallback final : public ServiceWorkerUpdateFinishCallback
@@ -281,12 +282,52 @@ public:
 
 class SWRUpdateRunnable final : public Runnable
 {
+  class TimerCallback final : public nsITimerCallback
+  {
+    RefPtr<ServiceWorkerPrivate> mPrivate;
+    RefPtr<Runnable> mRunnable;
+
+  public:
+    TimerCallback(ServiceWorkerPrivate* aPrivate,
+                  Runnable* aRunnable)
+      : mPrivate(aPrivate)
+      , mRunnable(aRunnable)
+    {
+      MOZ_ASSERT(mPrivate);
+      MOZ_ASSERT(aRunnable);
+    }
+
+    nsresult
+    Notify(nsITimer* aTimer) override
+    {
+      mRunnable->Run();
+      mPrivate->RemoveISupports(aTimer);
+
+      return NS_OK;
+    }
+
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+  private:
+    ~TimerCallback()
+    { }
+  };
+
 public:
-  SWRUpdateRunnable(PromiseWorkerProxy* aPromiseProxy, const nsAString& aScope)
+  explicit SWRUpdateRunnable(PromiseWorkerProxy* aPromiseProxy)
     : Runnable("dom::SWRUpdateRunnable")
     , mPromiseProxy(aPromiseProxy)
-    , mScope(aScope)
-  {}
+    , mDescriptor(aPromiseProxy->GetWorkerPrivate()->GetServiceWorkerDescriptor())
+    , mDelayed(false)
+  {
+    MOZ_ASSERT(mPromiseProxy);
+
+    // This runnable is used for update calls originating from a worker thread,
+    // which may be delayed in some cases.
+    MOZ_ASSERT(mPromiseProxy->GetWorkerPrivate()->IsServiceWorker());
+    MOZ_ASSERT(mPromiseProxy->GetWorkerPrivate());
+    mPromiseProxy->GetWorkerPrivate()->AssertIsOnWorkerThread();
+  }
 
   NS_IMETHOD
   Run() override
@@ -307,20 +348,65 @@ public:
     }
     MOZ_ASSERT(principal);
 
+    RefPtr<ServiceWorkerManager> swm = ServiceWorkerManager::GetInstance();
+    if (NS_WARN_IF(!swm)) {
+      return NS_OK;
+    }
+
+    // This will delay update jobs originating from a service worker thread.
+    // We don't currently handle ServiceWorkerRegistration.update() from other
+    // worker types. Also, we assume this registration matches self.registration
+    // on the service worker global. This is ok for now because service worker globals
+    // are the only worker contexts where we expose ServiceWorkerRegistration.
+    RefPtr<ServiceWorkerRegistrationInfo> registration =
+      swm->GetRegistration(principal, mDescriptor.Scope());
+    if (NS_WARN_IF(!registration)) {
+      return NS_OK;
+    }
+
+    RefPtr<ServiceWorkerInfo> worker = registration->GetByDescriptor(mDescriptor);
+    uint32_t delay = registration->GetUpdateDelay();
+
+    // if we have a timer object, it means we've already been delayed once.
+    if (delay && !mDelayed) {
+      nsCOMPtr<nsITimerCallback> cb = new TimerCallback(worker->WorkerPrivate(), this);
+      Result<nsCOMPtr<nsITimer>, nsresult> result =
+        NS_NewTimerWithCallback(cb, delay, nsITimer::TYPE_ONE_SHOT,
+                                SystemGroup::EventTargetFor(TaskCategory::Other));
+
+      nsCOMPtr<nsITimer> timer = result.unwrapOr(nullptr);
+      if (NS_WARN_IF(!timer)) {
+        return NS_OK;
+      }
+
+      mDelayed = true;
+      // We're storing the timer object on the calling service worker's private.
+      // ServiceWorkerPrivate will drop the reference if the worker terminates,
+      // which will cancel the timer.
+      worker->WorkerPrivate()->StoreISupports(timer);
+
+      return NS_OK;
+    }
+
     RefPtr<WorkerThreadUpdateCallback> cb =
       new WorkerThreadUpdateCallback(mPromiseProxy);
-    UpdateInternal(principal, mScope, cb);
+    UpdateInternal(principal, mDescriptor.Scope(), cb);
     return NS_OK;
   }
 
 private:
   ~SWRUpdateRunnable()
-  {}
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
 
   RefPtr<PromiseWorkerProxy> mPromiseProxy;
-  const nsString mScope;
+  const ServiceWorkerDescriptor mDescriptor;
+  bool mDelayed;
 };
 
+NS_IMPL_ISUPPORTS(SWRUpdateRunnable::TimerCallback, nsITimerCallback)
+
 class UnregisterCallback final : public nsIServiceWorkerUnregisterCallback
 {
   PromiseWindowProxy mPromise;
@@ -533,7 +619,7 @@ ServiceWorkerRegistrationMainThread::Update(ErrorResult& aRv)
 
   RefPtr<MainThreadUpdateCallback> cb =
     new MainThreadUpdateCallback(mOuter->GetOwner(), promise);
-  UpdateInternal(doc->NodePrincipal(), mScope, cb);
+  UpdateInternal(doc->NodePrincipal(), NS_ConvertUTF16toUTF8(mScope), cb);
 
   return promise.forget();
 }
@@ -848,7 +934,7 @@ ServiceWorkerRegistrationWorkerThread::Update(ErrorResult& aRv)
     return nullptr;
   }
 
-  RefPtr<SWRUpdateRunnable> r = new SWRUpdateRunnable(proxy, mScope);
+  RefPtr<SWRUpdateRunnable> r = new SWRUpdateRunnable(proxy);
   MOZ_ALWAYS_SUCCEEDS(worker->DispatchToMainThread(r.forget()));
 
   return promise.forget();
diff --git a/dom/serviceworkers/ServiceWorkerRegistrationInfo.cpp b/dom/serviceworkers/ServiceWorkerRegistrationInfo.cpp
index 4be02dc67467..baad25d5102c 100644
--- a/dom/serviceworkers/ServiceWorkerRegistrationInfo.cpp
+++ b/dom/serviceworkers/ServiceWorkerRegistrationInfo.cpp
@@ -87,6 +87,7 @@ ServiceWorkerRegistrationInfo::ServiceWorkerRegistrationInfo(
   : mPrincipal(aPrincipal)
   , mDescriptor(aPrincipal, aScope, aUpdateViaCache)
   , mControlledClientsCounter(0)
+  , mDelayMultiplier(0)
   , mUpdateState(NoUpdate)
   , mCreationTime(PR_Now())
   , mCreationTimeStamp(TimeStamp::Now())
@@ -709,5 +710,25 @@ ServiceWorkerRegistrationInfo::Descriptor() const
   return mDescriptor;
 }
 
+uint32_t
+ServiceWorkerRegistrationInfo::GetUpdateDelay()
+{
+  uint32_t delay = Preferences::GetInt("dom.serviceWorkers.update_delay",
+                                       1000);
+  // This can potentially happen if you spam registration->Update(). We don't
+  // want to wrap to a lower value.
+  if (mDelayMultiplier >= INT_MAX / (delay ? delay : 1)) {
+    return INT_MAX;
+  }
+
+  delay *= mDelayMultiplier;
+
+  if (!mControlledClientsCounter && mDelayMultiplier < (INT_MAX / 30)) {
+    mDelayMultiplier = (mDelayMultiplier ? mDelayMultiplier : 1) * 30;
+  }
+
+  return delay;
+}
+
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/serviceworkers/ServiceWorkerRegistrationInfo.h b/dom/serviceworkers/ServiceWorkerRegistrationInfo.h
index dd7c4fda278b..0e0736953d2d 100644
--- a/dom/serviceworkers/ServiceWorkerRegistrationInfo.h
+++ b/dom/serviceworkers/ServiceWorkerRegistrationInfo.h
@@ -23,6 +23,7 @@ class ServiceWorkerRegistrationInfo final
   nsTArray<nsCOMPtr<nsIServiceWorkerRegistrationInfoListener>> mListeners;
 
   uint32_t mControlledClientsCounter;
+  uint32_t mDelayMultiplier;
 
   enum
   {
@@ -94,6 +95,7 @@ public:
   StartControllingClient()
   {
     ++mControlledClientsCounter;
+    mDelayMultiplier = 0;
   }
 
   void
@@ -211,6 +213,9 @@ public:
   const ServiceWorkerRegistrationDescriptor&
   Descriptor() const;
 
+  uint32_t
+  GetUpdateDelay();
+
 private:
   // Roughly equivalent to [[Update Registration State algorithm]]. Make sure
   // this is called *before* updating SW instances' state, otherwise they
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 924f8823ab06..533029f80061 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -174,6 +174,10 @@ pref("dom.serviceWorkers.idle_timeout", 30000);
 // The amount of time (milliseconds) service workers can be kept running using waitUntil promises.
 pref("dom.serviceWorkers.idle_extended_timeout", 300000);
 
+// The amount of time (milliseconds) an update request is delayed when triggered
+// by a service worker that doesn't control any clients.
+pref("dom.serviceWorkers.update_delay", 1000);
+
 // Enable test for 24 hours update, service workers will always treat last update check time is over 24 hours
 pref("dom.serviceWorkers.testUpdateOverOneDay", false);