diff --git a/netwerk/protocol/http/HttpChannelChild.cpp b/netwerk/protocol/http/HttpChannelChild.cpp
index d06dc992df93..89d024c23692 100644
--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -2173,6 +2173,26 @@ NS_IMETHODIMP HttpChannelChild::GetClientSetRequestHeaders(RequestHeaderTuples *
   return NS_OK;
 }
 
+NS_IMETHODIMP
+HttpChannelChild::RemoveCorsPreflightCacheEntry(nsIURI* aURI,
+                                                nsIPrincipal* aPrincipal)
+{
+  URIParams uri;
+  SerializeURI(aURI, uri);
+  PrincipalInfo principalInfo;
+  nsresult rv = PrincipalToPrincipalInfo(aPrincipal, &principalInfo);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  bool result = false;
+  // Be careful to not attempt to send a message to the parent after the
+  // actor has been destroyed.
+  if (mIPCOpen) {
+    result = SendRemoveCorsPreflightCacheEntry(uri, principalInfo);
+  }
+  return result ? NS_OK : NS_ERROR_FAILURE;
+}
+
 //-----------------------------------------------------------------------------
 // HttpChannelChild::nsIDivertableChannel
 //-----------------------------------------------------------------------------
diff --git a/netwerk/protocol/http/HttpChannelParent.cpp b/netwerk/protocol/http/HttpChannelParent.cpp
index f01236df06ee..6cb370ca219e 100644
--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -34,6 +34,7 @@
 #include "nsIHttpHeaderVisitor.h"
 #include "nsQueryObject.h"
 #include "mozilla/BasePrincipal.h"
+#include "nsCORSListenerProxy.h"
 
 using mozilla::BasePrincipal;
 using mozilla::OriginAttributes;
@@ -939,6 +940,24 @@ HttpChannelParent::DivertComplete()
   mParentListener = nullptr;
 }
 
+bool
+HttpChannelParent::RecvRemoveCorsPreflightCacheEntry(const URIParams& uri,
+  const mozilla::ipc::PrincipalInfo& requestingPrincipal)
+{
+  nsCOMPtr<nsIURI> deserializedURI = DeserializeURI(uri);
+  if (!deserializedURI) {
+    return false;
+  }
+  nsCOMPtr<nsIPrincipal> principal =
+    PrincipalInfoToPrincipal(requestingPrincipal);
+  if (!principal) {
+    return false;
+  }
+  nsCORSListenerProxy::RemoveFromCorsPreflightCache(deserializedURI,
+                                                    principal);
+  return true;
+}
+
 //-----------------------------------------------------------------------------
 // HttpChannelParent::nsIRequestObserver
 //-----------------------------------------------------------------------------
diff --git a/netwerk/protocol/http/HttpChannelParent.h b/netwerk/protocol/http/HttpChannelParent.h
index 8788a862cf8e..8afe3237dc1a 100644
--- a/netwerk/protocol/http/HttpChannelParent.h
+++ b/netwerk/protocol/http/HttpChannelParent.h
@@ -141,6 +141,8 @@ protected:
                                          const uint32_t& count) override;
   virtual bool RecvDivertOnStopRequest(const nsresult& statusCode) override;
   virtual bool RecvDivertComplete() override;
+  virtual bool RecvRemoveCorsPreflightCacheEntry(const URIParams& uri,
+                                                 const mozilla::ipc::PrincipalInfo& requestingPrincipal) override;
   virtual void ActorDestroy(ActorDestroyReason why) override;
 
   // Supporting function for ADivertableParentChannel.
diff --git a/netwerk/protocol/http/PHttpChannel.ipdl b/netwerk/protocol/http/PHttpChannel.ipdl
index 4ead186b2867..1456b961acf0 100644
--- a/netwerk/protocol/http/PHttpChannel.ipdl
+++ b/netwerk/protocol/http/PHttpChannel.ipdl
@@ -8,6 +8,7 @@
 include protocol PNecko;
 include InputStreamParams;
 include URIParams;
+include PBackgroundSharedTypes;
 
 include protocol PBlob; //FIXME: bug #792908
 
@@ -79,6 +80,11 @@ parent:
   // Child has no more events/messages to divert to the parent.
   DivertComplete();
 
+  // Child has detected a CORS check failure, so needs to tell the parent
+  // to remove any matching entry from the CORS preflight cache.
+  RemoveCorsPreflightCacheEntry(URIParams uri,
+                                PrincipalInfo requestingPrincipal);
+
   __delete__();
 
 child:
diff --git a/netwerk/protocol/http/nsCORSListenerProxy.cpp b/netwerk/protocol/http/nsCORSListenerProxy.cpp
index 4ffcdc565e83..b1054891e562 100644
--- a/netwerk/protocol/http/nsCORSListenerProxy.cpp
+++ b/netwerk/protocol/http/nsCORSListenerProxy.cpp
@@ -10,6 +10,7 @@
 #include "nsCORSListenerProxy.h"
 #include "nsIChannel.h"
 #include "nsIHttpChannel.h"
+#include "nsIHttpChannelChild.h"
 #include "nsIHttpChannelInternal.h"
 #include "nsError.h"
 #include "nsContentUtils.h"
@@ -501,15 +502,24 @@ nsCORSListenerProxy::OnStartRequest(nsIRequest* aRequest,
   nsresult rv = CheckRequestApproved(aRequest);
   mRequestApproved = NS_SUCCEEDED(rv);
   if (!mRequestApproved) {
-    if (sPreflightCache) {
-      nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
-      if (channel) {
-        nsCOMPtr<nsIURI> uri;
-        NS_GetFinalChannelURI(channel, getter_AddRefs(uri));
-        if (uri) {
+    nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
+    if (channel) {
+      nsCOMPtr<nsIURI> uri;
+      NS_GetFinalChannelURI(channel, getter_AddRefs(uri));
+      if (uri) {
+        if (sPreflightCache) {
           // OK to use mRequestingPrincipal since preflights never get
           // redirected.
           sPreflightCache->RemoveEntries(uri, mRequestingPrincipal);
+        } else {
+          nsCOMPtr<nsIHttpChannelChild> httpChannelChild =
+            do_QueryInterface(channel);
+          if (httpChannelChild) {
+            rv = httpChannelChild->RemoveCorsPreflightCacheEntry(uri, mRequestingPrincipal);
+            if (NS_WARN_IF(NS_FAILED(rv))) {
+              return rv;
+            }
+          }
         }
       }
     }
@@ -732,13 +742,22 @@ nsCORSListenerProxy::AsyncOnChannelRedirect(nsIChannel *aOldChannel,
       !NS_IsHSTSUpgradeRedirect(aOldChannel, aNewChannel, aFlags)) {
     rv = CheckRequestApproved(aOldChannel);
     if (NS_FAILED(rv)) {
-      if (sPreflightCache) {
-        nsCOMPtr<nsIURI> oldURI;
-        NS_GetFinalChannelURI(aOldChannel, getter_AddRefs(oldURI));
-        if (oldURI) {
+      nsCOMPtr<nsIURI> oldURI;
+      NS_GetFinalChannelURI(aOldChannel, getter_AddRefs(oldURI));
+      if (oldURI) {
+        if (sPreflightCache) {
           // OK to use mRequestingPrincipal since preflights never get
           // redirected.
           sPreflightCache->RemoveEntries(oldURI, mRequestingPrincipal);
+        } else {
+          nsCOMPtr<nsIHttpChannelChild> httpChannelChild =
+            do_QueryInterface(aOldChannel);
+          if (httpChannelChild) {
+            rv = httpChannelChild->RemoveCorsPreflightCacheEntry(oldURI, mRequestingPrincipal);
+            if (NS_WARN_IF(NS_FAILED(rv))) {
+              return rv;
+            }
+          }
         }
       }
       aOldChannel->Cancel(NS_ERROR_DOM_BAD_URI);
@@ -1260,6 +1279,16 @@ nsCORSPreflightListener::GetInterface(const nsIID & aIID, void **aResult)
   return QueryInterface(aIID, aResult);
 }
 
+void
+nsCORSListenerProxy::RemoveFromCorsPreflightCache(nsIURI* aURI,
+                                                  nsIPrincipal* aRequestingPrincipal)
+{
+  MOZ_ASSERT(XRE_IsParentProcess());
+  if (sPreflightCache) {
+    sPreflightCache->RemoveEntries(aURI, aRequestingPrincipal);
+  }
+}
+
 nsresult
 NS_StartCORSPreflight(nsIChannel* aRequestChannel,
                       nsIStreamListener* aListener,
diff --git a/netwerk/protocol/http/nsCORSListenerProxy.h b/netwerk/protocol/http/nsCORSListenerProxy.h
index 8d790e8b0e5a..947d3e7a8ad6 100644
--- a/netwerk/protocol/http/nsCORSListenerProxy.h
+++ b/netwerk/protocol/http/nsCORSListenerProxy.h
@@ -33,6 +33,12 @@ NS_StartCORSPreflight(nsIChannel* aRequestChannel,
                       nsTArray<nsCString>& aACUnsafeHeaders,
                       nsIChannel** aPreflightChannel);
 
+namespace mozilla {
+namespace net {
+class HttpChannelParent;
+}
+}
+
 enum class DataURIHandling
 {
   Allow,
@@ -73,6 +79,12 @@ public:
   void SetInterceptController(nsINetworkInterceptController* aInterceptController);
 
 private:
+  // Only HttpChannelParent can call RemoveFromCorsPreflightCache
+  friend class mozilla::net::HttpChannelParent;
+
+  static void RemoveFromCorsPreflightCache(nsIURI* aURI,
+                                           nsIPrincipal* aRequestingPrincipal);
+
   ~nsCORSListenerProxy();
 
   nsresult UpdateChannel(nsIChannel* aChannel, DataURIHandling aAllowDataURI);
diff --git a/netwerk/protocol/http/nsIHttpChannelChild.idl b/netwerk/protocol/http/nsIHttpChannelChild.idl
index 93911f7c19ab..8d9e016163dd 100644
--- a/netwerk/protocol/http/nsIHttpChannelChild.idl
+++ b/netwerk/protocol/http/nsIHttpChannelChild.idl
@@ -7,7 +7,10 @@
 
 [ptr] native RequestHeaderTuples(mozilla::net::RequestHeaderTuples);
 
-[uuid(3842c5e9-b5b1-400c-8eb7-936a3316ff21)]
+interface nsIPrincipal;
+interface nsIURI;
+
+[uuid(81acb360-edd2-428e-935f-300a32efb649)]
 interface nsIHttpChannelChild : nsISupports
 {
   void addCookiesToRequest();
@@ -18,4 +21,8 @@ interface nsIHttpChannelChild : nsISupports
 
   // Headers that the channel client has set via SetRequestHeader.
   readonly attribute RequestHeaderTuples clientSetRequestHeaders;
+
+  // This method is called by nsCORSListenerProxy if we need to remove
+  // an entry from the CORS preflight cache in the parent process.
+  void removeCorsPreflightCacheEntry(in nsIURI aURI, in nsIPrincipal aRequestingPrincipal);
 };