diff --git a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java
index 7c83ceac517c..f795778e5e9b 100644
--- a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java
@@ -154,6 +154,8 @@ public class GeckoThread extends Thread {
         public Map<String, Object> prefs;
         public String userSerialNumber;
 
+        public boolean xpcshell;
+        public String outFilePath;
         public int prefsFd;
         public int prefMapFd;
         public int ipcFd;
@@ -274,17 +276,20 @@ public class GeckoThread extends Thread {
 
         // argv[0] is the program name, which for us is the package name.
         args.add(context.getPackageName());
-        args.add("-greomni");
-        args.add(context.getPackageResourcePath());
 
-        final GeckoProfile profile = getProfile();
-        if (profile.isCustomProfile()) {
-            args.add("-profile");
-            args.add(profile.getDir().getAbsolutePath());
-        } else {
-            profile.getDir(); // Make sure the profile dir exists.
-            args.add("-P");
-            args.add(profile.getName());
+        if (!mInitInfo.xpcshell) {
+            args.add("-greomni");
+            args.add(context.getPackageResourcePath());
+
+            final GeckoProfile profile = getProfile();
+            if (profile.isCustomProfile()) {
+                args.add("-profile");
+                args.add(profile.getDir().getAbsolutePath());
+            } else {
+                profile.getDir(); // Make sure the profile dir exists.
+                args.add("-P");
+                args.add(profile.getName());
+            }
         }
 
         if (mInitInfo.args != null) {
@@ -435,7 +440,8 @@ public class GeckoThread extends Thread {
         final boolean isChildProcess = isChildProcess();
 
         GeckoLoader.setupGeckoEnvironment(context, isChildProcess,
-                                          context.getFilesDir().getPath(), env, mInitInfo.prefs);
+                                          context.getFilesDir().getPath(), env, mInitInfo.prefs,
+                                          mInitInfo.xpcshell);
 
         initGeckoEnvironment();
 
@@ -465,7 +471,9 @@ public class GeckoThread extends Thread {
                               mInitInfo.extras.getInt(EXTRA_PREF_MAP_FD, -1),
                               mInitInfo.extras.getInt(EXTRA_IPC_FD, -1),
                               mInitInfo.extras.getInt(EXTRA_CRASH_FD, -1),
-                              mInitInfo.extras.getInt(EXTRA_CRASH_ANNOTATION_FD, -1));
+                              mInitInfo.extras.getInt(EXTRA_CRASH_ANNOTATION_FD, -1),
+                              isChildProcess ? false : mInitInfo.xpcshell,
+                              isChildProcess ? null : mInitInfo.outFilePath);
 
         // And... we're done.
         final boolean restarting = isState(State.RESTARTING);
diff --git a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/GeckoLoader.java b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/GeckoLoader.java
index fa0d2e797fe2..bed9c4f9e5ac 100644
--- a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/GeckoLoader.java
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/GeckoLoader.java
@@ -118,7 +118,8 @@ public final class GeckoLoader {
                                                           final boolean isChildProcess,
                                                           final String profilePath,
                                                           final Collection<String> env,
-                                                          final Map<String, Object> prefs) {
+                                                          final Map<String, Object> prefs,
+                                                          final boolean xpcshell) {
         for (final String e : env) {
             putenv(e);
         }
@@ -156,12 +157,15 @@ public final class GeckoLoader {
             setupInitialPrefs(prefs);
         }
 
-        // setup the tmp path
-        final File f = getTmpDir(context);
-        if (!f.exists()) {
-            f.mkdirs();
+        // Xpcshell tests set up their own temp directory
+        if (!xpcshell) {
+            // setup the tmp path
+            final File f = getTmpDir(context);
+            if (!f.exists()) {
+                f.mkdirs();
+            }
+            putenv("TMPDIR=" + f.getPath());
         }
-        putenv("TMPDIR=" + f.getPath());
 
         putenv("LANG=" + Locale.getDefault().toString());
 
@@ -496,7 +500,7 @@ public final class GeckoLoader {
     private static native void putenv(String map);
 
     // These methods are implemented in mozglue/android/APKOpen.cpp
-    public static native void nativeRun(String[] args, int prefsFd, int prefMapFd, int ipcFd, int crashFd, int crashAnnotationFd);
+    public static native void nativeRun(String[] args, int prefsFd, int prefMapFd, int ipcFd, int crashFd, int crashAnnotationFd, boolean xpcshell, String outFilePath);
     private static native void loadGeckoLibsNative();
     private static native void loadSQLiteLibsNative();
     private static native void loadNSSLibsNative();
diff --git a/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoRuntime.java b/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoRuntime.java
index 3852b79fc30a..9d26f0ec9160 100644
--- a/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoRuntime.java
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoRuntime.java
@@ -49,6 +49,7 @@ import org.mozilla.gecko.util.ThreadUtils;
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
@@ -289,6 +290,27 @@ public final class GeckoRuntime implements Parcelable {
         return null;
     }
 
+    private void setArguments(final Context context, final GeckoThread.InitInfo initInfo,
+                              final String[] arguments) {
+        final List<String> result = new ArrayList<>(arguments.length);
+        for (final String argument : arguments) {
+            if ("-xpcshell".equals(argument)) {
+                // Only debug builds of the test app can run an xpcshell
+                if (!BuildConfig.DEBUG
+                        || !"org.mozilla.geckoview.test".equals(
+                                context.getApplicationContext().getPackageName())) {
+                    throw new IllegalArgumentException("Only the test app can run -xpcshell.");
+                }
+
+                initInfo.xpcshell = true;
+            } else {
+                result.add(argument);
+            }
+        }
+
+        initInfo.args = result.toArray(new String[]{});
+    }
+
     /* package */ boolean init(final @NonNull Context context, final @NonNull GeckoRuntimeSettings settings) {
         if (DEBUG) {
             Log.d(LOGTAG, "init");
@@ -329,7 +351,10 @@ public final class GeckoRuntime implements Parcelable {
         GeckoFontScaleListener.getInstance().attachToContext(context, settings);
 
         final GeckoThread.InitInfo info = new GeckoThread.InitInfo();
-        info.args = settings.getArguments();
+        setArguments(context, info, settings.getArguments());
+        if (info.xpcshell) {
+            info.outFilePath = settings.getExtras().getString("out_file");
+        }
         info.extras = settings.getExtras();
         info.flags = flags;
 
diff --git a/mozglue/android/APKOpen.cpp b/mozglue/android/APKOpen.cpp
index e89d47e571f0..4fd7fe336a41 100644
--- a/mozglue/android/APKOpen.cpp
+++ b/mozglue/android/APKOpen.cpp
@@ -362,11 +362,10 @@ static void FreeArgv(char** argv, int argc) {
 }
 
 extern "C" APKOPEN_EXPORT void MOZ_JNICALL
-Java_org_mozilla_gecko_mozglue_GeckoLoader_nativeRun(JNIEnv* jenv, jclass jc,
-                                                     jobjectArray jargs,
-                                                     int prefsFd, int prefMapFd,
-                                                     int ipcFd, int crashFd,
-                                                     int crashAnnotationFd) {
+Java_org_mozilla_gecko_mozglue_GeckoLoader_nativeRun(
+    JNIEnv* jenv, jclass jc, jobjectArray jargs, int prefsFd, int prefMapFd,
+    int ipcFd, int crashFd, int crashAnnotationFd, bool xpcshell,
+    jstring outFilePath) {
   EnsureBaseProfilerInitialized();
 
   int argc = 0;
@@ -381,7 +380,15 @@ Java_org_mozilla_gecko_mozglue_GeckoLoader_nativeRun(JNIEnv* jenv, jclass jc,
 #ifdef MOZ_LINKER
     ElfLoader::Singleton.ExpectShutdown(false);
 #endif
-    gBootstrap->GeckoStart(jenv, argv, argc, sAppData);
+    const char* outFilePathRaw = nullptr;
+    if (xpcshell) {
+      MOZ_ASSERT(outFilePath);
+      outFilePathRaw = jenv->GetStringUTFChars(outFilePath, nullptr);
+    }
+    gBootstrap->GeckoStart(jenv, argv, argc, sAppData, xpcshell, outFilePathRaw);
+    if (outFilePathRaw) {
+      jenv->ReleaseStringUTFChars(outFilePath, outFilePathRaw);
+    }
 #ifdef MOZ_LINKER
     ElfLoader::Singleton.ExpectShutdown(true);
 #endif
diff --git a/toolkit/xre/Bootstrap.cpp b/toolkit/xre/Bootstrap.cpp
index 9f38cba8230c..11e6200fe3e9 100644
--- a/toolkit/xre/Bootstrap.cpp
+++ b/toolkit/xre/Bootstrap.cpp
@@ -73,8 +73,9 @@ class BootstrapImpl final : public Bootstrap {
 
 #ifdef MOZ_WIDGET_ANDROID
   virtual void GeckoStart(JNIEnv* aEnv, char** argv, int argc,
-                          const StaticXREAppData& aAppData) override {
-    ::GeckoStart(aEnv, argv, argc, aAppData);
+                          const StaticXREAppData& aAppData,
+                          bool xpcshell, const char* outFilePath) override {
+    ::GeckoStart(aEnv, argv, argc, aAppData, xpcshell, outFilePath);
   }
 
   virtual void XRE_SetAndroidChildFds(
diff --git a/toolkit/xre/Bootstrap.h b/toolkit/xre/Bootstrap.h
index 6310091da3cd..a17c209e4d01 100644
--- a/toolkit/xre/Bootstrap.h
+++ b/toolkit/xre/Bootstrap.h
@@ -28,7 +28,8 @@ struct StaticXREAppData;
 }
 
 extern "C" NS_EXPORT void GeckoStart(JNIEnv* aEnv, char** argv, int argc,
-                                     const mozilla::StaticXREAppData& aAppData);
+                                     const mozilla::StaticXREAppData& aAppData,
+                                     bool xpcshell, const char* outFilePath);
 #endif
 
 #if defined(XP_WIN) && defined(MOZ_SANDBOX)
@@ -120,7 +121,8 @@ class Bootstrap {
 
 #ifdef MOZ_WIDGET_ANDROID
   virtual void GeckoStart(JNIEnv* aEnv, char** argv, int argc,
-                          const StaticXREAppData& aAppData) = 0;
+                          const StaticXREAppData& aAppData, bool xpcshell,
+                          const char* outFilePath) = 0;
 
   virtual void XRE_SetAndroidChildFds(JNIEnv* aEnv,
                                       const XRE_AndroidChildFds& fds) = 0;
diff --git a/toolkit/xre/nsAndroidStartup.cpp b/toolkit/xre/nsAndroidStartup.cpp
index 8df017edc6fb..1512f53249e6 100644
--- a/toolkit/xre/nsAndroidStartup.cpp
+++ b/toolkit/xre/nsAndroidStartup.cpp
@@ -17,13 +17,15 @@
 #include "nsAppRunner.h"
 #include "nsExceptionHandler.h"
 #include "mozilla/Bootstrap.h"
+#include "XREShellData.h"
 
 #define LOG(args...) __android_log_print(ANDROID_LOG_INFO, MOZ_APP_NAME, args)
 
 using namespace mozilla;
 
 extern "C" NS_EXPORT void GeckoStart(JNIEnv* env, char** argv, int argc,
-                                     const StaticXREAppData& aAppData) {
+                                     const StaticXREAppData& aAppData,
+                                     bool xpcshell, const char* outFilePath) {
   mozilla::jni::SetGeckoThreadEnv(env);
 
   if (!argv) {
@@ -31,11 +33,26 @@ extern "C" NS_EXPORT void GeckoStart(JNIEnv* env, char** argv, int argc,
     return;
   }
 
-  BootstrapConfig config;
-  config.appData = &aAppData;
-  config.appDataPath = nullptr;
+  if (xpcshell) {
+    XREShellData shellData;
+    FILE* outFile = fopen(outFilePath, "w");
+    if (!outFile) {
+      LOG("XRE_XPCShellMain cannot open %s", outFilePath);
+      return;
+    }
+    // We redirect both stdout and stderr to the same file, to conform with
+    // what runxpcshell.py does on Desktop.
+    shellData.outFile = outFile;
+    shellData.errFile = outFile;
+    int result = XRE_XPCShellMain(argc, argv, nullptr, &shellData);
+    fclose(shellData.outFile);
+    if (result) LOG("XRE_XPCShellMain returned %d", result);
+  } else {
+    BootstrapConfig config;
+    config.appData = &aAppData;
+    config.appDataPath = nullptr;
 
-  int result = XRE_main(argc, argv, config);
-
-  if (result) LOG("XRE_main returned %d", result);
+    int result = XRE_main(argc, argv, config);
+    if (result) LOG("XRE_main returned %d", result);
+  }
 }