diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index dac2d206c0ba..79d088f70134 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -5379,6 +5379,14 @@ NS_IMETHODIMP
 nsDocShell::SetDefaultLoadFlags(uint32_t aDefaultLoadFlags)
 {
     mDefaultLoadFlags = aDefaultLoadFlags;
+
+    // Tell the load group to set these flags all requests in the group
+    if (mLoadGroup) {
+        mLoadGroup->SetDefaultLoadFlags(aDefaultLoadFlags);
+    } else {
+        NS_WARNING("nsDocShell::SetDefaultLoadFlags has no loadGroup to propagate the flags to");
+    }
+
     // Recursively tell all of our children.  We *do not* skip
     // <iframe mozbrowser> children - if someone sticks custom flags in this
     // docShell then they too get the same flags.
diff --git a/docshell/base/nsIDocShell.idl b/docshell/base/nsIDocShell.idl
index c077c169c915..0447f39733fe 100644
--- a/docshell/base/nsIDocShell.idl
+++ b/docshell/base/nsIDocShell.idl
@@ -356,7 +356,8 @@ interface nsIDocShell : nsIDocShellTreeItem
 
   /*
    * Default load flags (as defined in nsIRequest) that will be set on all
-   * requests made by this docShell and propagated to all child docShells.
+   * requests made by this docShell and propagated to all child docShells and
+   * to nsILoadGroup::defaultLoadFlags for the docShell's loadGroup.
    * Default is no flags.  Once set, only future requests initiated by the
    * docShell are affected, so in general, these flags should be set before
    * the docShell loads any content.
diff --git a/netwerk/base/public/nsILoadGroup.idl b/netwerk/base/public/nsILoadGroup.idl
index 308d9ce02506..5e219975f4a1 100644
--- a/netwerk/base/public/nsILoadGroup.idl
+++ b/netwerk/base/public/nsILoadGroup.idl
@@ -10,10 +10,12 @@ interface nsIRequestObserver;
 interface nsIInterfaceRequestor;
 interface nsILoadGroupConnectionInfo;
 
+typedef unsigned long nsLoadFlags;
+
 /**
  * A load group maintains a collection of nsIRequest objects. 
  */
-[scriptable, uuid(19501006-46e3-4634-b97d-26eff894b4d3)]
+[scriptable, uuid(afb57ac2-bce5-4ee3-bb34-385089a9ba5c)]
 interface nsILoadGroup : nsIRequest
 {
     /**
@@ -78,6 +80,19 @@ interface nsILoadGroup : nsIRequest
      * connection blocking, and per-tab connection grouping
      */
     readonly attribute nsILoadGroupConnectionInfo connectionInfo;
+
+    /**
+     * The set of load flags that will be added to all new requests added to
+     * this group. Any existing requests in the load group are not modified,
+     * so it is expected these flags will be added before requests are added
+     * to the group - typically via nsIDocShell::defaultLoadFlags on a new
+     * docShell.
+     * Note that these flags are *not* added to the default request for the
+     * load group; it is expected the default request will already have these
+     * flags (again, courtesy of setting nsIDocShell::defaultLoadFlags before
+     * the docShell has created the default request.)
+     */
+    attribute nsLoadFlags defaultLoadFlags;
 };
 
 %{C++
diff --git a/netwerk/base/src/nsLoadGroup.cpp b/netwerk/base/src/nsLoadGroup.cpp
index 65f7d7536288..bcc07a72dccb 100644
--- a/netwerk/base/src/nsLoadGroup.cpp
+++ b/netwerk/base/src/nsLoadGroup.cpp
@@ -115,6 +115,7 @@ RescheduleRequests(PLDHashTable *table, PLDHashEntryHdr *hdr,
 nsLoadGroup::nsLoadGroup(nsISupports* outer)
     : mForegroundCount(0)
     , mLoadFlags(LOAD_NORMAL)
+    , mDefaultLoadFlags(0)
     , mStatus(NS_OK)
     , mPriority(PRIORITY_NORMAL)
     , mIsCanceling(false)
@@ -859,6 +860,21 @@ nsLoadGroup::AdjustPriority(int32_t aDelta)
     return NS_OK;
 }
 
+NS_IMETHODIMP
+nsLoadGroup::GetDefaultLoadFlags(uint32_t *aFlags)
+{
+    *aFlags = mDefaultLoadFlags;
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLoadGroup::SetDefaultLoadFlags(uint32_t aFlags)
+{
+    mDefaultLoadFlags = aFlags;
+    return NS_OK;
+}
+
+
 ////////////////////////////////////////////////////////////////////////////////
 
 void 
@@ -1039,6 +1055,9 @@ nsresult nsLoadGroup::MergeLoadFlags(nsIRequest *aRequest, nsLoadFlags& outFlags
                             VALIDATE_ONCE_PER_SESSION |
                             VALIDATE_NEVER));
 
+    // ... and force the default flags.
+    flags |= mDefaultLoadFlags;
+
     if (flags != oldFlags)
         rv = aRequest->SetLoadFlags(flags);
 
diff --git a/netwerk/base/src/nsLoadGroup.h b/netwerk/base/src/nsLoadGroup.h
index e4d4d55dbbe4..32102c679cc1 100644
--- a/netwerk/base/src/nsLoadGroup.h
+++ b/netwerk/base/src/nsLoadGroup.h
@@ -70,6 +70,7 @@ private:
 protected:
     uint32_t                        mForegroundCount;
     uint32_t                        mLoadFlags;
+    uint32_t                        mDefaultLoadFlags;
 
     nsCOMPtr<nsILoadGroup>          mLoadGroup; // load groups can contain load groups
     nsCOMPtr<nsIInterfaceRequestor> mCallbacks;