--- a/xpcom/threads/nsProcess.h
+++ b/xpcom/threads/nsProcess.h
@@ -15,17 +15,17 @@
 #include "mozilla/Mutex.h"
 #include "nsIProcess.h"
 #include "nsIFile.h"
 #include "nsIThread.h"
 #include "nsIObserver.h"
 #include "nsIWeakReferenceUtils.h"
 #include "nsIObserver.h"
 #include "nsString.h"
-#ifndef XP_MACOSX
+#ifndef XP_UNIX
 #include "prproces.h"
 #endif
 #if defined(PROCESSMODEL_WINAPI)
 #include <windows.h>
 #include <shellapi.h>
 #endif
 
 #define NS_PROCESS_CID \
@@ -71,14 +71,14 @@ private:
   nsCOMPtr<nsIObserver> mObserver;
   nsWeakPtr mWeakObserver;
 
   // These members are modified by multiple threads, any accesses should be
   // protected with mLock.
   int32_t mExitValue;
 #if defined(PROCESSMODEL_WINAPI)
   HANDLE mProcess;
-#elif !defined(XP_MACOSX)
+#elif !defined(XP_UNIX)
   PRProcess* mProcess;
 #endif
 };
 
 #endif

--- a/xpcom/threads/nsProcessCommon.cpp
+++ b/xpcom/threads/nsProcessCommon.cpp
@@ -33,16 +33,21 @@
 #include "nsString.h"
 #include "nsLiteralString.h"
 #include "nsReadableUtils.h"
 #include "mozilla/UniquePtrExtensions.h"
 #else
 #ifdef XP_MACOSX
 #include <crt_externs.h>
 #include <spawn.h>
+#endif
+#ifdef XP_UNIX
+#ifndef XP_MACOSX
+#include "base/process_util.h"
+#endif
 #include <sys/wait.h>
 #include <sys/errno.h>
 #endif
 #include <sys/types.h>
 #include <signal.h>
 #endif
 
 using namespace mozilla;
@@ -73,17 +78,17 @@ nsProcess::nsProcess()
   , mShutdown(false)
   , mBlocking(false)
   , mStartHidden(false)
   , mNoShell(false)
   , mPid(-1)
   , mObserver(nullptr)
   , mWeakObserver(nullptr)
   , mExitValue(-1)
-#if !defined(XP_MACOSX)
+#if !defined(XP_UNIX)
   , mProcess(nullptr)
 #endif
 {
 }
 
 //Destructor
 nsProcess::~nsProcess()
 {
@@ -267,17 +272,17 @@ nsProcess::Monitor(void* aArg)
     CloseHandle(process->mProcess);
     process->mProcess = nullptr;
     process->mExitValue = exitCode;
     if (process->mShutdown) {
       return;
     }
   }
 #else
-#ifdef XP_MACOSX
+#ifdef XP_UNIX
   int exitCode = -1;
   int status = 0;
   pid_t result;
   do {
     result = waitpid(process->mPid, &status, 0);
   } while (result == -1 && errno == EINTR);
   if (result == process->mPid) {
     if (WIFEXITED(status)) {
@@ -291,17 +296,17 @@ nsProcess::Monitor(void* aArg)
   if (PR_WaitProcess(process->mProcess, &exitCode) != PR_SUCCESS) {
     exitCode = -1;
   }
 #endif
 
   // Lock in case Kill or GetExitCode are called during this
   {
     MutexAutoLock lock(process->mLock);
-#if !defined(XP_MACOSX)
+#if !defined(XP_UNIX)
     process->mProcess = nullptr;
 #endif
     process->mExitValue = exitCode;
     if (process->mShutdown) {
       return;
     }
   }
 #endif
@@ -565,16 +570,30 @@ nsProcess::RunProcess(bool aBlocking, ch
                             *_NSGetEnviron());
   mPid = static_cast<int32_t>(newPid);
 
   posix_spawnattr_destroy(&spawnattr);
 
   if (result != 0) {
     return NS_ERROR_FAILURE;
   }
+#elif defined(XP_UNIX)
+  base::file_handle_mapping_vector fdMap;
+  std::vector<std::string> argvVec;
+  for (char** arg = aMyArgv; *arg != nullptr; ++arg) {
+    argvVec.push_back(*arg);
+  }
+  pid_t newPid;
+  if (base::LaunchApp(argvVec, fdMap, false, &newPid)) {
+    static_assert(sizeof(pid_t) <= sizeof(int32_t),
+                  "mPid is large enough to hold a pid");
+    mPid = static_cast<int32_t>(newPid);
+  } else {
+    return NS_ERROR_FAILURE;
+  }
 #else
   mProcess = PR_CreateProcess(aMyArgv[0], aMyArgv, nullptr, nullptr);
   if (!mProcess) {
     return NS_ERROR_FAILURE;
   }
   struct MYProcess
   {
     uint32_t pid;
@@ -671,17 +690,17 @@ nsProcess::Kill()
   }
 
   {
     MutexAutoLock lock(mLock);
 #if defined(PROCESSMODEL_WINAPI)
     if (TerminateProcess(mProcess, 0) == 0) {
       return NS_ERROR_FAILURE;
     }
-#elif defined(XP_MACOSX)
+#elif defined(XP_UNIX)
     if (kill(mPid, SIGKILL) != 0) {
       return NS_ERROR_FAILURE;
     }
 #else
     if (!mProcess || (PR_KillProcess(mProcess) != PR_SUCCESS)) {
       return NS_ERROR_FAILURE;
     }
 #endif