diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index 323e2dc3a205..c09186f8a075 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -2603,13 +2603,8 @@ WarnIfSandboxIneffective(nsIDocShell* aDocShell,
 
 bool
 nsIDocument::IsSynthesized() {
-  nsCOMPtr<nsIHttpChannelInternal> internalChan = do_QueryInterface(mChannel);
-  bool synthesized = false;
-  if (internalChan) {
-    DebugOnly<nsresult> rv = internalChan->GetResponseSynthesized(&synthesized);
-    MOZ_ASSERT(NS_SUCCEEDED(rv), "GetResponseSynthesized shouldn't fail.");
-  }
-  return synthesized;
+  nsCOMPtr<nsILoadInfo> loadInfo = mChannel ? mChannel->GetLoadInfo() : nullptr;
+  return loadInfo && loadInfo->GetServiceWorkerTaintingSynthesized();
 }
 
 bool
diff --git a/netwerk/protocol/http/HttpBaseChannel.cpp b/netwerk/protocol/http/HttpBaseChannel.cpp
index e46ea4ec8536..0d3b8426a12f 100644
--- a/netwerk/protocol/http/HttpBaseChannel.cpp
+++ b/netwerk/protocol/http/HttpBaseChannel.cpp
@@ -472,21 +472,6 @@ HttpBaseChannel::GetLoadFlags(nsLoadFlags *aLoadFlags)
 NS_IMETHODIMP
 HttpBaseChannel::SetLoadFlags(nsLoadFlags aLoadFlags)
 {
-  bool synthesized = false;
-  nsresult rv = GetResponseSynthesized(&synthesized);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  // If this channel is marked as awaiting a synthesized response,
-  // modifying certain load flags can interfere with the implementation
-  // of the network interception logic. This takes care of a couple
-  // known cases that attempt to mark channels as anonymous due
-  // to cross-origin redirects; since the response is entirely synthesized
-  // this is an unnecessary precaution.
-  // This should be removed when bug 1201683 is fixed.
-  if (synthesized && aLoadFlags != mLoadFlags) {
-    aLoadFlags &= ~LOAD_ANONYMOUS;
-  }
-
   mLoadFlags = aLoadFlags;
   return NS_OK;
 }
diff --git a/netwerk/protocol/http/HttpChannelChild.cpp b/netwerk/protocol/http/HttpChannelChild.cpp
index beb893300206..dcb8e3eaf6d5 100644
--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -3638,14 +3638,6 @@ HttpChannelChild::ResetInterception()
   }
 }
 
-NS_IMETHODIMP
-HttpChannelChild::GetResponseSynthesized(bool* aSynthesized)
-{
-  NS_ENSURE_ARG_POINTER(aSynthesized);
-  *aSynthesized = mSynthesizedResponse;
-  return NS_OK;
-}
-
 void
 HttpChannelChild::TrySendDeletingChannel()
 {
diff --git a/netwerk/protocol/http/HttpChannelChild.h b/netwerk/protocol/http/HttpChannelChild.h
index 528c7d6c6a0a..3d585af56481 100644
--- a/netwerk/protocol/http/HttpChannelChild.h
+++ b/netwerk/protocol/http/HttpChannelChild.h
@@ -182,8 +182,6 @@ protected:
 
   virtual void DoAsyncAbort(nsresult aStatus) override;
 
-  NS_IMETHOD GetResponseSynthesized(bool* aSynthesized) override;
-
   nsresult
   AsyncCall(void (HttpChannelChild::*funcPtr)(),
             nsRunnableMethod<HttpChannelChild> **retval = nullptr) override;
diff --git a/netwerk/protocol/http/InterceptedHttpChannel.cpp b/netwerk/protocol/http/InterceptedHttpChannel.cpp
index 1babfefc622f..c3548a615227 100644
--- a/netwerk/protocol/http/InterceptedHttpChannel.cpp
+++ b/netwerk/protocol/http/InterceptedHttpChannel.cpp
@@ -607,13 +607,6 @@ InterceptedHttpChannel::SetupFallbackChannel(const char*  aFallbackKey)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-NS_IMETHODIMP
-InterceptedHttpChannel::GetResponseSynthesized(bool* aResponseSynthesized)
-{
-  *aResponseSynthesized = mResponseHead || mBodyReader;
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 InterceptedHttpChannel::SetPriority(int32_t aPriority)
 {
diff --git a/netwerk/protocol/http/InterceptedHttpChannel.h b/netwerk/protocol/http/InterceptedHttpChannel.h
index 1a14a365799e..cf8e380d77e4 100644
--- a/netwerk/protocol/http/InterceptedHttpChannel.h
+++ b/netwerk/protocol/http/InterceptedHttpChannel.h
@@ -173,9 +173,6 @@ public:
   NS_IMETHOD
   SetupFallbackChannel(const char * aFallbackKey) override;
 
-  NS_IMETHOD
-  GetResponseSynthesized(bool *aResponseSynthesized) override;
-
   NS_IMETHOD
   SetPriority(int32_t aPriority) override;
 
diff --git a/netwerk/protocol/http/nsCORSListenerProxy.cpp b/netwerk/protocol/http/nsCORSListenerProxy.cpp
index 2df0a7493ca2..53340cea9154 100644
--- a/netwerk/protocol/http/nsCORSListenerProxy.cpp
+++ b/netwerk/protocol/http/nsCORSListenerProxy.cpp
@@ -566,11 +566,8 @@ nsCORSListenerProxy::CheckRequestApproved(nsIRequest* aRequest)
     return NS_ERROR_DOM_BAD_URI;
   }
 
-  nsCOMPtr<nsIHttpChannelInternal> internal = do_QueryInterface(aRequest);
-  NS_ENSURE_STATE(internal);
-  bool responseSynthesized = false;
-  if (NS_SUCCEEDED(internal->GetResponseSynthesized(&responseSynthesized)) &&
-      responseSynthesized) {
+  nsCOMPtr<nsILoadInfo> loadInfo = http->GetLoadInfo();
+  if (loadInfo && loadInfo->GetServiceWorkerTaintingSynthesized()) {
     // For synthesized responses, we don't need to perform any checks.
     // Note: This would be unsafe if we ever changed our behavior to allow
     // service workers to intercept CORS preflights.
@@ -1270,15 +1267,9 @@ nsCORSPreflightListener::OnStartRequest(nsIRequest *aRequest,
 {
 #ifdef DEBUG
   {
-    nsCOMPtr<nsIHttpChannelInternal> internal = do_QueryInterface(aRequest);
-    bool responseSynthesized = false;
-    if (internal &&
-        NS_SUCCEEDED(internal->GetResponseSynthesized(&responseSynthesized))) {
-      // For synthesized responses, we don't need to perform any checks.
-      // This would be unsafe if we ever changed our behavior to allow
-      // service workers to intercept CORS preflights.
-      MOZ_ASSERT(!responseSynthesized);
-    }
+    nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
+    nsCOMPtr<nsILoadInfo> loadInfo = channel ? channel->GetLoadInfo() : nullptr;
+    MOZ_ASSERT(!loadInfo || !loadInfo->GetServiceWorkerTaintingSynthesized());
   }
 #endif
 
diff --git a/netwerk/protocol/http/nsHttpChannel.cpp b/netwerk/protocol/http/nsHttpChannel.cpp
index cef4c92097c6..60c4adcc3d32 100644
--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -8469,14 +8469,6 @@ nsHttpChannel::SetNotificationCallbacks(nsIInterfaceRequestor *aCallbacks)
     return rv;
 }
 
-NS_IMETHODIMP
-nsHttpChannel::GetResponseSynthesized(bool* aSynthesized)
-{
-    NS_ENSURE_ARG_POINTER(aSynthesized);
-    *aSynthesized = false;
-    return NS_OK;
-}
-
 bool
 nsHttpChannel::AwaitingCacheCallbacks()
 {
diff --git a/netwerk/protocol/http/nsHttpChannel.h b/netwerk/protocol/http/nsHttpChannel.h
index 24bd14f5fbc9..44a563e4c235 100644
--- a/netwerk/protocol/http/nsHttpChannel.h
+++ b/netwerk/protocol/http/nsHttpChannel.h
@@ -257,7 +257,6 @@ public: /* internal necko use only */
       uint32_t mKeep : 2;
     };
 
-    NS_IMETHOD GetResponseSynthesized(bool* aSynthesized) override;
     bool AwaitingCacheCallbacks();
     void SetCouldBeSynthesized();
 
diff --git a/netwerk/protocol/http/nsIHttpChannelInternal.idl b/netwerk/protocol/http/nsIHttpChannelInternal.idl
index 1b4d290e9fc6..686062fe0f91 100644
--- a/netwerk/protocol/http/nsIHttpChannelInternal.idl
+++ b/netwerk/protocol/http/nsIHttpChannelInternal.idl
@@ -231,8 +231,6 @@ interface nsIHttpChannelInternal : nsISupports
 
     [must_use] readonly attribute PRTime lastModifiedTime;
 
-    [must_use] readonly attribute boolean responseSynthesized;
-
     /**
      * Set by nsCORSListenerProxy if credentials should be included in
      * cross-origin requests. false indicates "same-origin", users should still