diff --git a/browser/app/nsBrowserApp.cpp b/browser/app/nsBrowserApp.cpp
index 022fbaed4586..51e99fc94634 100644
--- a/browser/app/nsBrowserApp.cpp
+++ b/browser/app/nsBrowserApp.cpp
@@ -232,9 +232,9 @@ static int do_main(int argc, char* argv[], char* envp[])
 }
 
 static nsresult
-InitXPCOMGlue()
+InitXPCOMGlue(const char *argv0)
 {
-  UniqueFreePtr<char> exePath = BinaryPath::Get();
+  UniqueFreePtr<char> exePath = BinaryPath::Get(argv0);
   if (!exePath) {
     Output("Couldn't find the application directory.\n");
     return NS_ERROR_FAILURE;
@@ -272,7 +272,7 @@ int main(int argc, char* argv[], char* envp[])
     }
 #endif
 
-    nsresult rv = InitXPCOMGlue();
+    nsresult rv = InitXPCOMGlue(argv[0]);
     if (NS_FAILED(rv)) {
       return 255;
     }
@@ -290,7 +290,7 @@ int main(int argc, char* argv[], char* envp[])
   DllBlocklist_Initialize();
 #endif
 
-  nsresult rv = InitXPCOMGlue();
+  nsresult rv = InitXPCOMGlue(argv[0]);
   if (NS_FAILED(rv)) {
     return 255;
   }
diff --git a/ipc/glue/ScopedXREEmbed.cpp b/ipc/glue/ScopedXREEmbed.cpp
index 4f19b9502b9a..b419fdb42175 100644
--- a/ipc/glue/ScopedXREEmbed.cpp
+++ b/ipc/glue/ScopedXREEmbed.cpp
@@ -46,8 +46,17 @@ ScopedXREEmbed::SetAppDir(const nsACString& aPath)
 void
 ScopedXREEmbed::Start()
 {
+  std::string path;
+#if defined(OS_WIN)
+  path = WideToUTF8(CommandLine::ForCurrentProcess()->program());
+#elif defined(OS_POSIX)
+  path = CommandLine::ForCurrentProcess()->argv()[0];
+#else
+#  error Sorry
+#endif
+
   nsCOMPtr<nsIFile> localFile;
-  nsresult rv = XRE_GetBinaryPath(getter_AddRefs(localFile));
+  nsresult rv = XRE_GetBinaryPath(path.c_str(), getter_AddRefs(localFile));
   if (NS_FAILED(rv))
     return;
 
diff --git a/js/xpconnect/src/XPCShellImpl.cpp b/js/xpconnect/src/XPCShellImpl.cpp
index 0c4841ad690f..c0749a6af63f 100644
--- a/js/xpconnect/src/XPCShellImpl.cpp
+++ b/js/xpconnect/src/XPCShellImpl.cpp
@@ -1115,7 +1115,7 @@ XRE_XPCShellMain(int argc, char** argv, char** envp,
 
     { // Start scoping nsCOMPtrs
         nsCOMPtr<nsIFile> appFile;
-        rv = XRE_GetBinaryPath(getter_AddRefs(appFile));
+        rv = XRE_GetBinaryPath(argv[0], getter_AddRefs(appFile));
         if (NS_FAILED(rv)) {
             printf("Couldn't find application file.\n");
             return 1;
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index 97e68fc1e468..6ec497033ebf 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -1875,9 +1875,9 @@ XRE_InitOmnijar(nsIFile* greOmni, nsIFile* appOmni)
 }
 
 nsresult
-XRE_GetBinaryPath(nsIFile* *aResult)
+XRE_GetBinaryPath(const char* argv0, nsIFile* *aResult)
 {
-  return mozilla::BinaryPath::GetFile(aResult);
+  return mozilla::BinaryPath::GetFile(argv0, aResult);
 }
 
 #ifdef XP_WIN
@@ -1916,7 +1916,7 @@ static nsresult LaunchChild(nsINativeAppSupport* aNative,
   LaunchChildMac(gRestartArgc, gRestartArgv);
 #else
   nsCOMPtr<nsIFile> lf;
-  nsresult rv = XRE_GetBinaryPath(getter_AddRefs(lf));
+  nsresult rv = XRE_GetBinaryPath(gArgv[0], getter_AddRefs(lf));
   if (NS_FAILED(rv))
     return rv;
 
@@ -4785,7 +4785,7 @@ XREMain::XRE_main(int argc, char* argv[], const BootstrapConfig& aConfig)
   gAppData = mAppData.get();
 
   nsCOMPtr<nsIFile> binFile;
-  rv = XRE_GetBinaryPath(getter_AddRefs(binFile));
+  rv = XRE_GetBinaryPath(argv[0], getter_AddRefs(binFile));
   NS_ENSURE_SUCCESS(rv, 1);
 
   rv = binFile->GetPath(gAbsoluteArgv0Path);
@@ -4793,7 +4793,7 @@ XREMain::XRE_main(int argc, char* argv[], const BootstrapConfig& aConfig)
 
   if (!mAppData->xreDirectory) {
     nsCOMPtr<nsIFile> lf;
-    rv = XRE_GetBinaryPath(getter_AddRefs(lf));
+    rv = XRE_GetBinaryPath(gArgv[0], getter_AddRefs(lf));
     if (NS_FAILED(rv))
       return 2;
 
@@ -4976,7 +4976,7 @@ XRE_InitCommandLine(int aArgc, char* aArgv[])
 
   // get the canonical version of the binary's path
   nsCOMPtr<nsIFile> binFile;
-  rv = XRE_GetBinaryPath(getter_AddRefs(binFile));
+  rv = XRE_GetBinaryPath(aArgv[0], getter_AddRefs(binFile));
   if (NS_FAILED(rv))
     return NS_ERROR_FAILURE;
 
diff --git a/toolkit/xre/nsUpdateDriver.cpp b/toolkit/xre/nsUpdateDriver.cpp
index 5f56f753cb5b..bdbc1cf27a57 100644
--- a/toolkit/xre/nsUpdateDriver.cpp
+++ b/toolkit/xre/nsUpdateDriver.cpp
@@ -508,7 +508,7 @@ ApplyUpdate(nsIFile *greDir, nsIFile *updateDir, nsIFile *appDir, int appArgc,
     // Get the application file path used by the updater to restart the
     // application after the update has finished.
     nsCOMPtr<nsIFile> appFile;
-    XRE_GetBinaryPath(getter_AddRefs(appFile));
+    XRE_GetBinaryPath(appArgv[0], getter_AddRefs(appFile));
     if (!appFile) {
       return;
     }
diff --git a/toolkit/xre/nsXREDirProvider.cpp b/toolkit/xre/nsXREDirProvider.cpp
index 546612d39562..08e31da5a484 100644
--- a/toolkit/xre/nsXREDirProvider.cpp
+++ b/toolkit/xre/nsXREDirProvider.cpp
@@ -426,9 +426,9 @@ nsXREDirProvider::GetFile(const char* aProperty, bool* aPersistent,
   else if (!strcmp(aProperty, NS_APP_USER_PROFILES_LOCAL_ROOT_DIR)) {
     rv = GetUserProfilesLocalDir(getter_AddRefs(file), nullptr, nullptr, nullptr);
   }
-  else if (!strcmp(aProperty, XRE_EXECUTABLE_FILE)) {
+  else if (!strcmp(aProperty, XRE_EXECUTABLE_FILE) && gArgv[0]) {
     nsCOMPtr<nsIFile> lf;
-    rv = XRE_GetBinaryPath(getter_AddRefs(lf));
+    rv = XRE_GetBinaryPath(gArgv[0], getter_AddRefs(lf));
     if (NS_SUCCEEDED(rv))
       file = lf;
   }
@@ -928,7 +928,7 @@ nsXREDirProvider::GetFilesInternal(const char* aProperty,
 
     if (mozilla::Preferences::GetBool("plugins.load_appdir_plugins", false)) {
       nsCOMPtr<nsIFile> appdir;
-      rv = XRE_GetBinaryPath(getter_AddRefs(appdir));
+      rv = XRE_GetBinaryPath(gArgv[0], getter_AddRefs(appdir));
       if (NS_SUCCEEDED(rv)) {
         appdir->SetNativeLeafName(NS_LITERAL_CSTRING("plugins"));
         directories.AppendObject(appdir);
diff --git a/xpcom/build/BinaryPath.h b/xpcom/build/BinaryPath.h
index a078695af25b..617fd2e0b9d1 100644
--- a/xpcom/build/BinaryPath.h
+++ b/xpcom/build/BinaryPath.h
@@ -13,17 +13,8 @@
 #elif defined(XP_MACOSX)
 #include <CoreFoundation/CoreFoundation.h>
 #elif defined(XP_UNIX)
-#include <unistd.h>
-#include <stdlib.h>
-#include <string.h>
-#endif
-#if defined(__FreeBSD__) || defined(__DragonFly__) || \
-    defined(__FreeBSD_kernel__) || defined(__NetBSD__) || \
-    defined(__OpenBSD__)
-#include <sys/sysctl.h>
-#endif
-#if defined(__OpenBSD__)
 #include <sys/stat.h>
+#include <string.h>
 #endif
 #include "mozilla/UniquePtr.h"
 #include "mozilla/UniquePtrExtensions.h"
@@ -40,10 +31,10 @@ class BinaryPath
 {
 public:
 #ifdef XP_WIN
-  static nsresult Get(char aResult[MAXPATHLEN])
+  static nsresult Get(const char* argv0, char aResult[MAXPATHLEN])
   {
     wchar_t wide_path[MAXPATHLEN];
-    nsresult rv = GetW(wide_path);
+    nsresult rv = GetW(argv0, wide_path);
     if (NS_FAILED(rv)) {
       return rv;
     }
@@ -58,7 +49,7 @@ public:
     static wchar_t exeLongPath[MAXPATHLEN] = L"";
 
     if (!cached) {
-      nsresult rv = GetW(exeLongPath);
+      nsresult rv = GetW(nullptr, exeLongPath);
 
       if (NS_FAILED(rv)) {
         return rv;
@@ -79,7 +70,7 @@ public:
   }
 
 private:
-  static nsresult GetW(wchar_t aResult[MAXPATHLEN])
+  static nsresult GetW(const char* argv0, wchar_t aResult[MAXPATHLEN])
   {
     static bool cached = false;
     static wchar_t moduleFileName[MAXPATHLEN] = L"";
@@ -100,7 +91,7 @@ private:
   }
 
 #elif defined(XP_MACOSX)
-  static nsresult Get(char aResult[MAXPATHLEN])
+  static nsresult Get(const char* argv0, char aResult[MAXPATHLEN])
   {
     // Works even if we're not bundled.
     CFBundleRef appBundle = CFBundleGetMainBundle();
@@ -140,7 +131,7 @@ private:
   }
 
 #elif defined(ANDROID)
-  static nsresult Get(char aResult[MAXPATHLEN])
+  static nsresult Get(const char* argv0, char aResult[MAXPATHLEN])
   {
     // On Android, we use the GRE_HOME variable that is set by the Java
     // bootstrap code.
@@ -154,72 +145,14 @@ private:
     return NS_OK;
   }
 
-#elif defined(XP_LINUX) || defined(XP_SOLARIS)
-  static nsresult Get(char aResult[MAXPATHLEN])
-  {
-#  if defined(XP_SOLARIS)
-    const char path[] = "/proc/self/path/a.out";
-#  else
-    const char path[] = "/proc/self/exe";
-#  endif
-
-    ssize_t len = readlink(path, aResult, MAXPATHLEN - 1);
-    if (len < 0) {
-      return NS_ERROR_FAILURE;
-    }
-    aResult[len] = '\0';
-    return NS_OK;
-  }
-
-#elif defined(__FreeBSD__) || defined(__DragonFly__) || \
-      defined(__FreeBSD_kernel__) || defined(__NetBSD__)
-  static nsresult Get(char aResult[MAXPATHLEN])
-  {
-    int mib[4];
-    mib[0] = CTL_KERN;
-#ifdef __NetBSD__
-    mib[1] = KERN_PROC_ARGS;
-    mib[2] = -1;
-    mib[3] = KERN_PROC_PATHNAME;
-#else
-    mib[1] = KERN_PROC;
-    mib[2] = KERN_PROC_PATHNAME;
-    mib[3] = -1;
-#endif
-
-    size_t len = MAXPATHLEN;
-    if (sysctl(mib, 4, aResult, &len, nullptr, 0) < 0) {
-      return NS_ERROR_FAILURE;
-    }
-
-    return NS_OK;
-  }
-
-#elif defined(__OpenBSD__)
-  static nsresult Get(char aResult[MAXPATHLEN])
-  {
-    int mib[4];
-    mib[0] = CTL_KERN;
-    mib[1] = KERN_PROC_ARGS;
-    mib[2] = getpid();
-    mib[3] = KERN_PROC_ARGV;
-
-    size_t len = 0;
-    if (sysctl(mib, 4, nullptr, &len, nullptr, 0) < 0) {
-      return NS_ERROR_FAILURE;
-    }
-
-    auto argv = MakeUnique<const char*[]>(len / sizeof(const char*));
-    if (sysctl(mib, 4, argv.get(), &len, nullptr, 0) < 0) {
-      return NS_ERROR_FAILURE;
-    }
-
-    return GetFromArgv0(argv[0], aResult);
-  }
-
-  static nsresult GetFromArgv0(const char* aArgv0, char aResult[MAXPATHLEN])
+#elif defined(XP_UNIX)
+  static nsresult Get(const char* aArgv0, char aResult[MAXPATHLEN])
   {
     struct stat fileStat;
+    // on unix, there is no official way to get the path of the current binary.
+    // instead of using the MOZILLA_FIVE_HOME hack, which doesn't scale to
+    // multiple applications, we will try a series of techniques:
+    //
     // 1) use realpath() on argv[0], which works unless we're loaded from the
     //    PATH. Only do so if argv[0] looks like a path (contains a /).
     // 2) manually walk through the PATH and look for ourself
@@ -262,10 +195,10 @@ private:
 #endif
 
 public:
-  static UniqueFreePtr<char> Get()
+  static UniqueFreePtr<char> Get(const char *aArgv0)
   {
     char path[MAXPATHLEN];
-    if (NS_FAILED(Get(path))) {
+    if (NS_FAILED(Get(aArgv0, path))) {
       return nullptr;
     }
     UniqueFreePtr<char> result;
@@ -274,15 +207,15 @@ public:
   }
 
 #ifdef MOZILLA_INTERNAL_API
-  static nsresult GetFile(nsIFile** aResult)
+  static nsresult GetFile(const char* aArgv0, nsIFile** aResult)
   {
     nsCOMPtr<nsIFile> lf;
 #ifdef XP_WIN
     wchar_t exePath[MAXPATHLEN];
-    nsresult rv = GetW(exePath);
+    nsresult rv = GetW(aArgv0, exePath);
 #else
     char exePath[MAXPATHLEN];
-    nsresult rv = Get(exePath);
+    nsresult rv = Get(aArgv0, exePath);
 #endif
     if (NS_FAILED(rv)) {
       return rv;
diff --git a/xpcom/build/nsXULAppAPI.h b/xpcom/build/nsXULAppAPI.h
index 293d10617170..e172b492dd27 100644
--- a/xpcom/build/nsXULAppAPI.h
+++ b/xpcom/build/nsXULAppAPI.h
@@ -205,9 +205,12 @@ XRE_API(nsresult,
 
 /**
  * Get the path of the running application binary and store it in aResult.
+ * @param aArgv0  The value passed as argv[0] of main(). This value is only
+ *                used on *nix, and only when other methods of determining
+ *                the binary path have failed.
  */
 XRE_API(nsresult,
-        XRE_GetBinaryPath, (nsIFile** aResult))
+        XRE_GetBinaryPath, (const char* aArgv0, nsIFile** aResult))
 
 /**
  * Get the static module built in to libxul.