diff --git a/.hgignore b/.hgignore
index c398e60c0033..349b9404ebf9 100644
--- a/.hgignore
+++ b/.hgignore
@@ -35,6 +35,7 @@ compile_commands\.json
 ^\.clang-tidy
 ^\.mozconfig
 ^mozconfig*
+^\.moz-fast-forward
 ^old-configure$
 ^config\.cache$
 ^config\.log$
diff --git a/dom/media/webrtc/third_party_build/use_config_env.sh b/dom/media/webrtc/third_party_build/use_config_env.sh
index 90d950a6fe85..f05fca74a839 100644
--- a/dom/media/webrtc/third_party_build/use_config_env.sh
+++ b/dom/media/webrtc/third_party_build/use_config_env.sh
@@ -1,10 +1,28 @@
 #!/bin/bash
 
-SCRIPT_DIR="dom/media/webrtc/third_party_build"
+# Assume that if STATE_DIR is already defined, we do not need to
+# execute this file again.
+if [ "x$STATE_DIR" != "x" ]; then
+  # no need to run script since we've already run
+  return
+fi
+
+export SCRIPT_DIR="dom/media/webrtc/third_party_build"
+# first, make sure we're running from the top of moz-central repo
+if [ ! -d $SCRIPT_DIR ]; then
+  echo "Error: unable to find directory $SCRIPT_DIR"
+  exit 1
+fi
+
+# Should we tie the location of the STATE_DIR to the path
+# in MOZ_CONFIG_PATH?  Probably.
+export STATE_DIR=`pwd`/.moz-fast-forward
+export LOG_DIR=$STATE_DIR/logs
+export TMP_DIR=$STATE_DIR/tmp
 
 # Allow user to override default path to config_env
 if [ "x$MOZ_CONFIG_PATH" = "x" ]; then
-  MOZ_CONFIG_PATH=~/config_env
+  MOZ_CONFIG_PATH=$STATE_DIR/config_env
   echo "Using default MOZ_CONFIG_PATH=$MOZ_CONFIG_PATH"
 fi
 
@@ -19,6 +37,36 @@ if [ ! -f $MOZ_CONFIG_PATH ]; then
 fi
 source $MOZ_CONFIG_PATH
 
+if [ ! -d $STATE_DIR ]; then
+  echo "Creating missing $STATE_DIR"
+  mkdir -p $STATE_DIR
+  if [ ! -d $STATE_DIR ]; then
+    echo "error: unable to find (or create) $STATE_DIR"
+    exit 1
+  fi
+fi
+echo "Using STATE_DIR=$STATE_DIR"
+
+if [ ! -d $LOG_DIR ]; then
+  echo "Creating missing $LOG_DIR"
+  mkdir -p $LOG_DIR
+  if [ ! -d $LOG_DIR ]; then
+    echo "error: unable to find (or create) $LOG_DIR"
+    exit 1
+  fi
+fi
+echo "Using LOG_DIR=$LOG_DIR"
+
+if [ ! -d $TMP_DIR ]; then
+  echo "Creating missing $TMP_DIR"
+  mkdir -p $TMP_DIR
+  if [ ! -d $TMP_DIR ]; then
+    echo "error: unable to find (or create) $TMP_DIR"
+    exit 1
+  fi
+fi
+echo "Using TMP_DIR=$TMP_DIR"
+
 function find_base_commit()
 {
   # read the last line of README.moz-ff-commit to retrieve our current base
@@ -33,6 +81,7 @@ function find_base_commit()
   MOZ_LIBWEBRTC_BASE=`cd $MOZ_LIBWEBRTC_SRC ; git rev-parse --short $MOZ_LIBWEBRTC_BASE`
   echo "adjusted MOZ_LIBWEBRTC_BASE: $MOZ_LIBWEBRTC_BASE"
 }
+export -f find_base_commit
 
 function find_next_commit()
 {
@@ -41,3 +90,4 @@ function find_next_commit()
   git log --oneline --ancestry-path $MOZ_LIBWEBRTC_BASE^..$MOZ_TARGET_UPSTREAM_BRANCH_HEAD \
    | tail -2 | head -1 | awk '{print $1;}'`
 }
+export -f find_next_commit