--- a/build/automation.py.in
+++ b/build/automation.py.in
@@ -194,17 +194,16 @@ class Automation(object):
     preloadEnvVar = None
     if self.UNIXISH or self.IS_MAC:
       envVar = "LD_LIBRARY_PATH"
       preloadEnvVar = "LD_PRELOAD"
       if self.IS_MAC:
         envVar = "DYLD_LIBRARY_PATH"
         dmdLibrary = "libdmd.dylib"
       else: # unixish
-        env['MOZILLA_FIVE_HOME'] = xrePath
         dmdLibrary = "libdmd.so"
       if envVar in env:
         ldLibraryPath = ldLibraryPath + ":" + env[envVar]
       env[envVar] = ldLibraryPath
     elif self.IS_WIN32:
       env["PATH"] = env["PATH"] + ";" + str(ldLibraryPath)
       dmdLibrary = "dmd.dll"
       preloadEnvVar = "MOZ_REPLACE_MALLOC_LIB"

--- a/build/unix/run-mozilla.sh
+++ b/build/unix/run-mozilla.sh
@@ -232,23 +232,18 @@ fi
 ##
 ## Make sure the program is executable
 ##
 if [ ! -x "$MOZ_PROGRAM" ]
 then
 	moz_bail "Cannot execute $MOZ_PROGRAM."
 fi
 #
-##
-## Set MOZILLA_FIVE_HOME
-##
-MOZILLA_FIVE_HOME=$MOZ_DIST_BIN
-
 if [ -z "$MRE_HOME" ]; then
-    MRE_HOME=$MOZILLA_FIVE_HOME
+    MRE_HOME=$MOZ_DIST_BIN"
 fi
 ##
 ## Set LD_LIBRARY_PATH
 ##
 ## On Solaris we use $ORIGIN (set in RUNPATH) instead of LD_LIBRARY_PATH 
 ## to locate shared libraries. 
 ##
 ## When a shared library is a symbolic link, $ORIGIN will be replaced with
@@ -310,17 +305,16 @@ then
 fi
 
 # Disable Gnome crash dialog
 GNOME_DISABLE_CRASH_DIALOG=1
 export GNOME_DISABLE_CRASH_DIALOG
 
 if [ "$moz_debug" -eq 1 ]
 then
-  echo "MOZILLA_FIVE_HOME=$MOZILLA_FIVE_HOME"
   echo "  LD_LIBRARY_PATH=$LD_LIBRARY_PATH"
   if [ -n "$LD_LIBRARYN32_PATH" ]
   then
   	echo "LD_LIBRARYN32_PATH=$LD_LIBRARYN32_PATH"
   fi
   if [ -n "$LD_LIBRARYN64_PATH" ]
   then
   	echo "LD_LIBRARYN64_PATH=$LD_LIBRARYN64_PATH"
@@ -344,17 +338,17 @@ then
   echo "       ADDON_PATH=$ADDON_PATH"
   echo "      MOZ_PROGRAM=$MOZ_PROGRAM"
   echo "      MOZ_TOOLKIT=$MOZ_TOOLKIT"
   echo "        moz_debug=$moz_debug"
   echo "     moz_debugger=$moz_debugger"
   echo "moz_debugger_args=$moz_debugger_args"
 fi
 #
-export MOZILLA_FIVE_HOME LD_LIBRARY_PATH
+export LD_LIBRARY_PATH
 export SHLIB_PATH LIBPATH LIBRARY_PATH ADDON_PATH DYLD_LIBRARY_PATH
 
 if [ $moz_debug -eq 1 ]
 then
 	moz_debug_program ${1+"$@"}
 else
 	moz_run_program ${1+"$@"}
 fi

--- a/testing/gtest/rungtests.py
+++ b/testing/gtest/rungtests.py
@@ -76,17 +76,16 @@ class GTests(object):
         if not result:
             log.testFail("gtest | test failed with return code %d", proc.proc.returncode)
         return result
 
     def build_core_environment(self, env = {}):
         """
         Add environment variables likely to be used across all platforms, including remote systems.
         """
-        env["MOZILLA_FIVE_HOME"] = self.xre_path
         env["MOZ_XRE_DIR"] = self.xre_path
         env["MOZ_GMP_PATH"] = os.pathsep.join(
             os.path.join(self.xre_path, p, "1.0")
             for p in ('gmp-fake', 'gmp-fakeopenh264')
         )
         env["XPCOM_DEBUG_BREAK"] = "stack-and-abort"
         env["MOZ_CRASHREPORTER_NO_REPORT"] = "1"
         env["MOZ_CRASHREPORTER"] = "1"

--- a/testing/mozbase/mozrunner/mozrunner/utils.py
+++ b/testing/mozbase/mozrunner/mozrunner/utils.py
@@ -99,17 +99,16 @@ def test_environment(xrePath, env=None, 
     else:
         ldLibraryPath = xrePath
 
     envVar = None
     dmdLibrary = None
     preloadEnvVar = None
     if mozinfo.isUnix:
         envVar = "LD_LIBRARY_PATH"
-        env['MOZILLA_FIVE_HOME'] = xrePath
         dmdLibrary = "libdmd.so"
         preloadEnvVar = "LD_PRELOAD"
     elif mozinfo.isMac:
         envVar = "DYLD_LIBRARY_PATH"
         dmdLibrary = "libdmd.dylib"
         preloadEnvVar = "DYLD_INSERT_LIBRARIES"
     elif mozinfo.isWin:
         envVar = "PATH"

--- a/testing/remotecppunittests.py
+++ b/testing/remotecppunittests.py
@@ -102,17 +102,16 @@ class RemoteCPPUnitTests(cppunittests.CP
                 self.remote_bin_dir, os.path.basename(local_file))
             self.device.pushFile(local_file, remote_file)
 
     def build_environment(self):
         env = self.build_core_environment()
         env['LD_LIBRARY_PATH'] = self.remote_bin_dir
         env["TMPDIR"] = self.remote_tmp_dir
         env["HOME"] = self.remote_home_dir
-        env["MOZILLA_FIVE_HOME"] = self.remote_home_dir
         env["MOZ_XRE_DIR"] = self.remote_bin_dir
         if self.options.add_env:
             for envdef in self.options.add_env:
                 envdef_parts = envdef.split("=", 1)
                 if len(envdef_parts) == 2:
                     env[envdef_parts[0]] = envdef_parts[1]
                 elif len(envdef_parts) == 1:
                     env[envdef_parts[0]] = ""

--- a/testing/runcppunittests.py
+++ b/testing/runcppunittests.py
@@ -79,17 +79,16 @@ class CPPUnitTests(object):
             else:
                 self.log.test_end(basename, status='PASS', expected='PASS')
             return result
 
     def build_core_environment(self, env={}):
         """
         Add environment variables likely to be used across all platforms, including remote systems.
         """
-        env["MOZILLA_FIVE_HOME"] = self.xre_path
         env["MOZ_XRE_DIR"] = self.xre_path
         # TODO: switch this to just abort once all C++ unit tests have
         # been fixed to enable crash reporting
         env["XPCOM_DEBUG_BREAK"] = "stack-and-abort"
         env["MOZ_CRASHREPORTER_NO_REPORT"] = "1"
         env["MOZ_CRASHREPORTER"] = "1"
         return env