diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index bfd13920ad45..e3461160666e 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -79,6 +79,7 @@
 #include "nsThreadManager.h"
 #include "nsAnonymousTemporaryFile.h"
 #include "nsISpellChecker.h"
+#include "nsClipboardProxy.h"
 
 #include "IHistory.h"
 #include "nsNetUtil.h"
@@ -717,9 +718,16 @@ ContentChild::InitXPCOM()
         NS_WARNING("Couldn't register console listener for child process");
 
     bool isOffline;
-    SendGetXPCOMProcessAttributes(&isOffline, &mAvailableDictionaries);
+    ClipboardCapabilities clipboardCaps;
+    SendGetXPCOMProcessAttributes(&isOffline, &mAvailableDictionaries, &clipboardCaps);
     RecvSetOffline(isOffline);
 
+    nsCOMPtr<nsIClipboard> clipboard(do_GetService("@mozilla.org/widget/clipboard;1"));
+    MOZ_ASSERT(clipboard, "should have gotten a clipboard proxy");
+
+    auto clipboardProxy = static_cast<nsClipboardProxy *>(clipboard.get());
+    clipboardProxy->SetCapabilities(clipboardCaps);
+
     DebugOnly<FileUpdateDispatcher*> observer = FileUpdateDispatcher::GetSingleton();
     NS_ASSERTION(observer, "FileUpdateDispatcher is null");
 
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index d9bdcf1713c3..b3ade7486cd7 100755
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -2498,8 +2498,13 @@ ContentParent::RecvAddNewProcess(const uint32_t& aPid,
     // Update offline settings.
     bool isOffline;
     InfallibleTArray<nsString> unusedDictionaries;
-    RecvGetXPCOMProcessAttributes(&isOffline, &unusedDictionaries);
+    ClipboardCapabilities clipboardCaps;
+    RecvGetXPCOMProcessAttributes(&isOffline, &unusedDictionaries,
+                                  &clipboardCaps);
     content->SendSetOffline(isOffline);
+    MOZ_ASSERT(!clipboardCaps.supportsSelectionClipboard() &&
+               !clipboardCaps.supportsFindClipboard(),
+               "Unexpected values");
 
     PreallocatedProcessManager::PublishSpareProcess(content);
     return true;
@@ -2747,7 +2752,8 @@ ContentParent::RecvGetProcessAttributes(uint64_t* aId,
 
 bool
 ContentParent::RecvGetXPCOMProcessAttributes(bool* aIsOffline,
-                                             InfallibleTArray<nsString>* dictionaries)
+                                             InfallibleTArray<nsString>* dictionaries,
+                                             ClipboardCapabilities* clipboardCaps)
 {
     nsCOMPtr<nsIIOService> io(do_GetIOService());
     MOZ_ASSERT(io, "No IO service?");
@@ -2759,6 +2765,15 @@ ContentParent::RecvGetXPCOMProcessAttributes(bool* aIsOffline,
 
     spellChecker->GetDictionaryList(dictionaries);
 
+    nsCOMPtr<nsIClipboard> clipboard(do_GetService("@mozilla.org/widget/clipboard;1"));
+    MOZ_ASSERT(clipboard, "No clipboard?");
+
+    rv = clipboard->SupportsSelectionClipboard(&clipboardCaps->supportsSelectionClipboard());
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+    rv = clipboard->SupportsFindClipboard(&clipboardCaps->supportsFindClipboard());
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+
     return true;
 }
 
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index c38705e98149..0c27d575814d 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -413,7 +413,8 @@ private:
                                           bool* aIsForApp,
                                           bool* aIsForBrowser) MOZ_OVERRIDE;
     virtual bool RecvGetXPCOMProcessAttributes(bool* aIsOffline,
-                                               InfallibleTArray<nsString>* dictionaries)
+                                               InfallibleTArray<nsString>* dictionaries,
+                                               ClipboardCapabilities* clipboardCaps)
         MOZ_OVERRIDE;
 
     virtual bool DeallocPJavaScriptParent(mozilla::jsipc::PJavaScriptParent*) MOZ_OVERRIDE;
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index c8d3defa0767..0378dc846b02 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -314,6 +314,11 @@ struct VolumeInfo {
   bool isUnmounting;
 };
 
+struct ClipboardCapabilities {
+  bool supportsSelectionClipboard;
+  bool supportsFindClipboard;
+};
+
 union MaybeFileDesc {
     FileDescriptor;
     void_t;
@@ -507,7 +512,8 @@ parent:
     sync GetProcessAttributes()
         returns (uint64_t id, bool isForApp, bool isForBrowser);
     sync GetXPCOMProcessAttributes()
-        returns (bool isOffline, nsString[] dictionaries);
+        returns (bool isOffline, nsString[] dictionaries,
+                 ClipboardCapabilities clipboardCaps);
 
     sync CreateChildProcess(IPCTabContext context,
                             ProcessPriority priority)
diff --git a/widget/xpwidgets/nsClipboardProxy.cpp b/widget/xpwidgets/nsClipboardProxy.cpp
index 2f345a419672..f0efebab18cb 100644
--- a/widget/xpwidgets/nsClipboardProxy.cpp
+++ b/widget/xpwidgets/nsClipboardProxy.cpp
@@ -10,17 +10,18 @@
 #include "nsXULAppAPI.h"
 
 using namespace mozilla;
-using mozilla::dom::ContentChild;
+using namespace mozilla::dom;
 
 NS_IMPL_ISUPPORTS(nsClipboardProxy, nsIClipboard)
 
 nsClipboardProxy::nsClipboardProxy()
+  : mClipboardCaps(false, false)
 {
 }
 
 NS_IMETHODIMP
 nsClipboardProxy::SetData(nsITransferable *aTransferable,
-			  nsIClipboardOwner *anOwner, int32_t aWhichClipboard)
+                          nsIClipboardOwner *anOwner, int32_t aWhichClipboard)
 {
   nsCOMPtr<nsISupports> tmp;
   uint32_t len;
@@ -36,7 +37,7 @@ nsClipboardProxy::SetData(nsITransferable *aTransferable,
   bool isPrivateData = false;
   aTransferable->GetIsPrivateData(&isPrivateData);
   ContentChild::GetSingleton()->SendSetClipboardText(buffer, isPrivateData,
-						     aWhichClipboard);
+                                                     aWhichClipboard);
 
   return NS_OK;
 }
@@ -87,7 +88,7 @@ nsClipboardProxy::HasDataMatchingFlavors(const char **aFlavorList,
 NS_IMETHODIMP
 nsClipboardProxy::SupportsSelectionClipboard(bool *aIsSupported)
 {
-  *aIsSupported = false;
+  *aIsSupported = mClipboardCaps.supportsSelectionClipboard();
   return NS_OK;
 }
 
@@ -95,6 +96,12 @@ nsClipboardProxy::SupportsSelectionClipboard(bool *aIsSupported)
 NS_IMETHODIMP
 nsClipboardProxy::SupportsFindClipboard(bool *aIsSupported)
 {
-  *aIsSupported = false;
+  *aIsSupported = mClipboardCaps.supportsFindClipboard();
   return NS_OK;
 }
+
+void
+nsClipboardProxy::SetCapabilities(const ClipboardCapabilities& aClipboardCaps)
+{
+  mClipboardCaps = aClipboardCaps;
+}
diff --git a/widget/xpwidgets/nsClipboardProxy.h b/widget/xpwidgets/nsClipboardProxy.h
index c4bd70da70b3..1deafa955916 100644
--- a/widget/xpwidgets/nsClipboardProxy.h
+++ b/widget/xpwidgets/nsClipboardProxy.h
@@ -7,16 +7,24 @@
 #define NS_CLIPBOARD_PROXY_H
 
 #include "nsIClipboard.h"
+#include "mozilla/dom/PContent.h"
 
 class nsClipboardProxy MOZ_FINAL : public nsIClipboard
 {
-  ~nsClipboardProxy() {}
+  typedef mozilla::dom::ClipboardCapabilities ClipboardCapabilities;
 
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSICLIPBOARD
 
   nsClipboardProxy();
+
+  void SetCapabilities(const ClipboardCapabilities& aClipboardCaps);
+
+private:
+  ~nsClipboardProxy() {}
+
+  ClipboardCapabilities mClipboardCaps;
 };
 
 #endif