--- a/dom/media/gmp/moz.build
+++ b/dom/media/gmp/moz.build
@@ -69,19 +69,19 @@ EXPORTS += [
     'GMPVideoEncoderChild.h',
     'GMPVideoEncoderParent.h',
     'GMPVideoEncoderProxy.h',
     'GMPVideoHost.h',
     'GMPVideoi420FrameImpl.h',
     'GMPVideoPlaneImpl.h',
 ]
 
-# We link GMPLoader into xul on B2G/Fennec as its code does not need to be
-# covered by a DRM vendor's voucher.
-if CONFIG['OS_TARGET'] == 'Android':
+# We link GMPLoader into xul on Android and Linux as its code does not
+# need to be covered by a DRM vendor's voucher.
+if CONFIG['OS_ARCH'] == 'Linux':
     SOURCES += [
       'GMPLoader.cpp',
     ]
     USE_LIBS += [
         'rlz',
     ]
 
 UNIFIED_SOURCES += [

--- a/ipc/app/moz.build
+++ b/ipc/app/moz.build
@@ -24,17 +24,17 @@ include('/ipc/chromium/chromium-config.m
 
 LOCAL_INCLUDES += [
     '/toolkit/xre',
     '/xpcom/base',
 ]
 
 # We link GMPLoader into plugin-container on desktop so that its code is
 # covered by the desktop DRM vendor's voucher.
-if CONFIG['OS_TARGET'] != 'Android':
+if CONFIG['OS_ARCH'] != 'Linux':
     SOURCES += [
         '../../dom/media/gmp/GMPLoader.cpp',
     ]
     USE_LIBS += [
         'rlz',
     ]
 
 # DELAYLOAD_DLLS in this block ensures that the DLL blocklist is functional

--- a/ipc/contentproc/plugin-container.cpp
+++ b/ipc/contentproc/plugin-container.cpp
@@ -78,36 +78,16 @@ public:
         if (IsSandboxedProcess()) {
             mozilla::sandboxing::LowerSandbox();
         }
         return true;
     }
 };
 #endif
 
-#if defined(XP_LINUX) && defined(MOZ_GMP_SANDBOX)
-class LinuxSandboxStarter : public mozilla::gmp::SandboxStarter {
-    LinuxSandboxStarter() { }
-public:
-    static SandboxStarter* Make() {
-        if (mozilla::SandboxInfo::Get().CanSandboxMedia()) {
-            return new LinuxSandboxStarter();
-        } else {
-            // Sandboxing isn't possible, but the parent has already
-            // checked that this plugin doesn't require it.  (Bug 1074561)
-            return nullptr;
-        }
-    }
-    virtual bool Start(const char *aLibPath) override {
-        mozilla::SetMediaPluginSandbox(aLibPath);
-        return true;
-    }
-};
-#endif
-
 #if defined(XP_MACOSX) && defined(MOZ_GMP_SANDBOX)
 class MacSandboxStarter : public mozilla::gmp::SandboxStarter {
 public:
     virtual bool Start(const char *aLibPath) override {
       std::string err;
       bool rv = mozilla::StartMacSandbox(mInfo, err);
       if (!rv) {
         fprintf(stderr, "sandbox_init() failed! Error \"%s\"\n", err.c_str());
@@ -122,18 +102,16 @@ private:
 };
 #endif
 
 mozilla::gmp::SandboxStarter*
 MakeSandboxStarter()
 {
 #if defined(XP_WIN) && defined(MOZ_SANDBOX)
     return new WinSandboxStarter();
-#elif defined(XP_LINUX) && defined(MOZ_GMP_SANDBOX)
-    return LinuxSandboxStarter::Make();
 #elif defined(XP_MACOSX) && defined(MOZ_GMP_SANDBOX)
     return new MacSandboxStarter();
 #else
     return nullptr;
 #endif
 }
 
 int
@@ -181,18 +159,18 @@ content_process_main(int argc, char* arg
     // For plugins, this is done in PluginProcessChild::Init, as we need to
     // avoid it for unsupported plugins.  See PluginProcessChild::Init for
     // the details.
     if (XRE_GetProcessType() != GeckoProcessType_Plugin) {
         mozilla::SanitizeEnvironmentVariables();
         SetDllDirectoryW(L"");
     }
 #endif
-#if !defined(MOZ_WIDGET_ANDROID) && !defined(MOZ_WIDGET_GONK) && defined(MOZ_PLUGIN_CONTAINER)
-    // On desktop, the GMPLoader lives in plugin-container, so that its
+#if !defined(XP_LINUX) && defined(MOZ_PLUGIN_CONTAINER)
+    // On Windows and MacOS, the GMPLoader lives in plugin-container, so that its
     // code can be covered by an EME/GMP vendor's voucher.
     nsAutoPtr<mozilla::gmp::SandboxStarter> starter(MakeSandboxStarter());
     if (XRE_GetProcessType() == GeckoProcessType_GMPlugin) {
         childData.gmpLoader = mozilla::gmp::CreateGMPLoader(starter);
     }
 #endif
     nsresult rv = XRE_InitChildProcess(argc, argv, &childData);
     NS_ENSURE_SUCCESS(rv, 1);

--- a/toolkit/xre/moz.build
+++ b/toolkit/xre/moz.build
@@ -149,16 +149,21 @@ LOCAL_INCLUDES += [
 ]
 
 if CONFIG['MOZ_SANDBOX'] and CONFIG['OS_ARCH'] == 'WINNT':
     LOCAL_INCLUDES += [
         '/security/sandbox/chromium',
         '/security/sandbox/chromium-shim',
     ]
 
+if CONFIG['MOZ_SANDBOX'] and CONFIG['OS_ARCH'] == 'Linux':
+    USE_LIBS += [
+        'mozsandbox',
+    ]
+
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
     LOCAL_INCLUDES += [
         '/widget',
         '/widget/cocoa',
     ]
 
 if CONFIG['MOZ_ENABLE_XREMOTE']:
     LOCAL_INCLUDES += [

--- a/toolkit/xre/nsEmbedFunctions.cpp
+++ b/toolkit/xre/nsEmbedFunctions.cpp
@@ -81,16 +81,21 @@
 #include "mozilla/sandboxTarget.h"
 #include "mozilla/sandboxing/loggingCallbacks.h"
 #endif
 
 #if defined(MOZ_CONTENT_SANDBOX) && !defined(MOZ_WIDGET_GONK)
 #include "mozilla/Preferences.h"
 #endif
 
+#if defined(XP_LINUX) && defined(MOZ_GMP_SANDBOX)
+#include "mozilla/Sandbox.h"
+#include "mozilla/SandboxInfo.h"
+#endif
+
 #ifdef MOZ_IPDL_TESTS
 #include "mozilla/_ipdltest/IPDLUnitTests.h"
 #include "mozilla/_ipdltest/IPDLUnitTestProcessChild.h"
 
 using mozilla::_ipdltest::IPDLUnitTestProcessChild;
 #endif  // ifdef MOZ_IPDL_TESTS
 
 #ifdef MOZ_JPROF
@@ -318,41 +323,72 @@ AddContentSandboxLevelAnnotation()
     levelString.AppendInt(level);
     CrashReporter::AnnotateCrashReport(
       NS_LITERAL_CSTRING("ContentSandboxLevel"), levelString);
   }
 }
 #endif /* MOZ_CONTENT_SANDBOX && !MOZ_WIDGET_GONK */
 #endif /* MOZ_CRASHREPORTER */
 
+#if defined (XP_LINUX) && defined(MOZ_GMP_SANDBOX)
+namespace {
+class LinuxSandboxStarter : public mozilla::gmp::SandboxStarter {
+  LinuxSandboxStarter() { }
+public:
+  static SandboxStarter* Make() {
+    if (mozilla::SandboxInfo::Get().CanSandboxMedia()) {
+      return new LinuxSandboxStarter();
+    } else {
+      // Sandboxing isn't possible, but the parent has already
+      // checked that this plugin doesn't require it.  (Bug 1074561)
+      return nullptr;
+    }
+    return nullptr;
+  }
+  virtual bool Start(const char *aLibPath) override {
+    mozilla::SetMediaPluginSandbox(aLibPath);
+    return true;
+  }
+};
+} // anonymous namespace
+#endif // XP_LINUX && MOZ_GMP_SANDBOX
+
 nsresult
 XRE_InitChildProcess(int aArgc,
                      char* aArgv[],
                      const XREChildData* aChildData)
 {
   NS_ENSURE_ARG_MIN(aArgc, 2);
   NS_ENSURE_ARG_POINTER(aArgv);
   NS_ENSURE_ARG_POINTER(aArgv[0]);
   MOZ_ASSERT(aChildData);
 
 #ifdef MOZ_JPROF
   // Call the code to install our handler
   setupProfilingStuff();
 #endif
 
-#if !defined(MOZ_WIDGET_ANDROID) && !defined(MOZ_WIDGET_GONK)
-  // On non-Fennec Gecko, the GMPLoader code resides in plugin-container,
-  // and we must forward it through to the GMP code here.
-  GMPProcessChild::SetGMPLoader(aChildData->gmpLoader.get());
-#else
+#ifdef XP_LINUX
   // On Fennec, the GMPLoader's code resides inside XUL (because for the time
   // being GMPLoader relies upon NSPR, which we can't use in plugin-container
   // on Android), so we create it here inside XUL and pass it to the GMP code.
-  UniquePtr<GMPLoader> loader = CreateGMPLoader(nullptr);
+  //
+  // On desktop Linux, the sandbox code lives in a shared library, and
+  // the GMPLoader is in libxul instead of executables to avoid unwanted
+  // library dependencies.
+  mozilla::gmp::SandboxStarter* starter = nullptr;
+#ifdef MOZ_GMP_SANDBOX
+  starter = LinuxSandboxStarter::Make();
+#endif
+  UniquePtr<GMPLoader> loader = CreateGMPLoader(starter);
   GMPProcessChild::SetGMPLoader(loader.get());
+#else
+  // On non-Linux platforms, the GMPLoader code resides in plugin-container,
+  // and we must forward it through to the GMP code here.
+  GMPProcessChild::SetGMPLoader(aChildData->gmpLoader.get());
 #endif
 
 #if defined(XP_WIN)
   // From the --attach-console support in nsNativeAppSupportWin.cpp, but
   // here we are a content child process, so we always attempt to attach
   // to the parent's (ie, the browser's) console.
   // Try to attach console to the parent process.
   // It will succeed when the parent process is a command line,