diff --git a/build_image b/build_image
index 3eb32e4a8c..2f418bf865 100755
--- a/build_image
+++ b/build_image
@@ -39,8 +39,6 @@ DEFINE_boolean statefuldev $FLAGS_TRUE \
   "Install development packages on stateful partition rather than the rootfs"
 DEFINE_string to "" \
   "The target image file or device"
-DEFINE_boolean withtest $FLAGS_FALSE \
-  "Include packages required for testing and prepare image for testing"
 DEFINE_string arm_extra_bootargs "" \
   "Additional command line options to pass to the ARM kernel."
 
@@ -167,34 +165,6 @@ delete_prompt() {
 # translate to /usr/local
 DEV_IMAGE_ROOT=
 
-# Sets up symlinks for the stateful partition based on the root specified by
-# ${1} and var directory specified by ${2}.
-setup_symlinks_on_root() {
-  echo "Setting up symlinks on the stateful partition rooted at ${1} with"\
-    "var directory located at ${2}"
-
-  for path in usr local; do
-    if [ -h "${DEV_IMAGE_ROOT}/${path}" ] ; then
-      sudo unlink "${DEV_IMAGE_ROOT}/${path}"
-    elif [ -e "${DEV_IMAGE_ROOT}/${path}" ] ; then
-      echo "*** ERROR: ${DEV_IMAGE_ROOT}/${path} should be a symlink if exists"
-      return 1
-    fi
-    sudo ln -s ${1} "${DEV_IMAGE_ROOT}/${path}"
-  done
-
-  # Setup var.  Var is on the stateful partition at /var for both non-developer
-  # builds and developer builds.
-  if [ -h "${DEV_IMAGE_ROOT}/var" ] ; then
-    sudo unlink "${DEV_IMAGE_ROOT}/var"
-  elif [ -e "${DEV_IMAGE_ROOT}/var" ] ; then
-    echo "*** ERROR: ${DEV_IMAGE_ROOT}/var should be a symlink if it exists"
-    return 1
-  fi
-
-  sudo ln -s "${2}" "${DEV_IMAGE_ROOT}/var"
-}
-
 trap "cleanup && delete_prompt" EXIT
 
 mkdir -p "$ROOT_FS_DIR"
@@ -299,7 +269,8 @@ sudo mkdir -p "${STATEFUL_DIR}/var"
 
 # Create symlinks so that /usr/local/usr based directories are symlinked to
 # /usr/local/ directories e.g. /usr/local/usr/bin -> /usr/local/bin, etc.
-setup_symlinks_on_root "${DEV_IMAGE_ROOT}" "${STATEFUL_DIR}/var"
+setup_symlinks_on_root "${DEV_IMAGE_ROOT}" "${STATEFUL_DIR}/var" \
+  "${STATEFUL_DIR}"
 
 # Perform binding rather than symlinking because directories must exist
 # on rootfs so that we can bind at run-time since rootfs is read-only
@@ -335,13 +306,6 @@ if [[ $FLAGS_withdev -eq $FLAGS_TRUE ]] ; then
   sudo cp -a "$(which ldd)" "${ROOT_DEV_DIR}/usr/bin"
 fi
 
-# Install packages required for testing.
-if [[ $FLAGS_withtest -eq $FLAGS_TRUE ]] ; then
-  sudo INSTALL_MASK="$INSTALL_MASK" emerge-${BOARD} \
-      --root="$ROOT_DEV_DIR" --root-deps=rdeps \
-      --usepkgonly chromeos-test $EMERGE_JOBS
-fi
-
 # Extract the kernel from the root filesystem for use by the GPT image. Legacy
 # BIOS will use the kernel in the rootfs (via syslinux), Chrome OS BIOS will
 # use the kernel partition.
@@ -414,7 +378,7 @@ fi
 # Clean up symlinks so they work on a running target rooted at "/".
 # Here development packages are rooted at /usr/local.  However, do not
 # create /usr/local or /var on host (already exist on target).
-setup_symlinks_on_root "/usr/local" "/var"
+setup_symlinks_on_root "/usr/local" "/var" "${STATEFUL_DIR}"
 
 # Cleanup loop devices.
 cleanup
diff --git a/common.sh b/common.sh
index 201679eb4b..9121a24f72 100644
--- a/common.sh
+++ b/common.sh
@@ -362,3 +362,44 @@ function safe_umount {
     sudo umount -d -l "${path}" || die "Failed to lazily unmount ${path}"
   fi
 }
+
+# Sets up symlinks for the developer root. It is necessary to symlink
+# usr and local since the developer root is mounted at /usr/local and
+# applications expect to be installed under /usr/local/bin, etc.
+# This avoids packages installing into /usr/local/usr/local/bin.
+# ${1} specifies the symlink target for the developer root.
+# ${2} specifies the symlink target for the var directory.
+# ${3} specifies the location of the stateful partition.
+setup_symlinks_on_root() {
+  # Give args better names.
+  local dev_image_target=${1}
+  local var_target=${2}
+  local dev_image_root="${3}/dev_image"
+
+  # If our var target is actually the standard var, we are cleaning up the
+  # symlinks (could also check for /usr/local for the dev_image_target).
+  if [ ${var_target} = "/var" ]; then
+    echo "Cleaning up /usr/local symlinks for ${dev_image_root}"
+  else
+    echo "Setting up symlinks for /usr/local for ${dev_image_root}"
+  fi
+
+  # Set up symlinks that should point to ${dev_image_target}.
+  for path in usr local; do
+    if [ -h "${dev_image_root}/${path}" ]; then
+      sudo unlink "${dev_image_root}/${path}"
+    elif [ -e "${dev_image_root}/${path}" ]; then
+      die "${dev_image_root}/${path} should be a symlink if exists"
+    fi
+    sudo ln -s ${dev_image_target} "${dev_image_root}/${path}"
+  done
+
+  # Setup var symlink.
+  if [ -h "${dev_image_root}/var" ]; then
+    sudo unlink "${dev_image_root}/var"
+  elif [ -e "${dev_image_root}/var" ]; then
+    die "${dev_image_root}/var should be a symlink if it exists"
+  fi
+
+  sudo ln -s "${var_target}" "${dev_image_root}/var"
+}
diff --git a/mod_image_for_test.sh b/mod_image_for_test.sh
index 8bcdcbd642..ddf060c7af 100755
--- a/mod_image_for_test.sh
+++ b/mod_image_for_test.sh
@@ -13,16 +13,24 @@
 # Load functions and constants for chromeos-install
 . "$(dirname "$0")/chromeos-common.sh"
 
+# We need to be in the chroot to emerge test packages.
+assert_inside_chroot
+
 get_default_board
 
-DEFINE_string board "$DEFAULT_BOARD" "Board for which the image was built"
-DEFINE_string qualdb "/tmp/run_remote_tests.*" \
-    "Location of qualified component file"
-DEFINE_string image "" "Location of the rootfs raw image file"
-DEFINE_boolean factory $FLAGS_FALSE "Modify the image for manufacturing testing"
+DEFINE_string board "$DEFAULT_BOARD" "Board for which the image was built" b
+DEFINE_boolean factory $FLAGS_FALSE \
+  "Modify the image for manufacturing testing" f
 DEFINE_boolean factory_install $FLAGS_FALSE \
     "Modify the image for factory install shim"
-DEFINE_boolean yes $FLAGS_FALSE "Answer yes to all prompts" "y"
+DEFINE_string image "" "Location of the rootfs raw image file" i
+DEFINE_boolean installmask $FLAGS_TRUE \
+  "Use INSTALL_MASK to shrink the resulting image." m
+DEFINE_integer jobs -1 \
+  "How many packages to build in parallel at maximum." j
+DEFINE_string qualdb "/tmp/run_remote_tests.*" \
+    "Location of qualified component file" d
+DEFINE_boolean yes $FLAGS_FALSE "Answer yes to all prompts" y
 
 # Parse command line
 FLAGS "$@" || exit 1
@@ -31,8 +39,7 @@ eval set -- "${FLAGS_ARGV}"
 # No board, no default and no image set then we can't find the image
 if [ -z $FLAGS_image ] && [ -z $FLAGS_board ] ; then
   setup_board_warning
-  echo "*** mod_image_for_test failed.  No board set and no image set"
-  exit 1
+  die "mod_image_for_test failed.  No board set and no image set"
 fi
 
 # We have a board name but no image set.  Use image at default location
@@ -42,6 +49,9 @@ if [ -z $FLAGS_image ] ; then
   FLAGS_image="${IMAGES_DIR}/$(ls -t $IMAGES_DIR 2>&-| head -1)/${FILENAME}"
 fi
 
+# Turn path into an absolute path.
+FLAGS_image=`eval readlink -f ${FLAGS_image}`
+
 # Abort early if we can't find the image
 if [ ! -f $FLAGS_image ] ; then
   echo "No image found at $FLAGS_image"
@@ -62,33 +72,23 @@ cleanup_mounts() {
   done
 }
 
-cleanup_loop() {
-  sudo umount "$1"
-  sleep 1  # in case the loop device is in use
-  sudo losetup -d "$1"
+cleanup() {
+  "$SCRIPTS_DIR/mount_gpt_image.sh" -u -r "$ROOT_FS_DIR" -s "$STATEFUL_DIR"
 }
 
-cleanup() {
-  # Disable die on error.
-  set +e
-
-  cleanup_mounts "${ROOT_FS_DIR}"
-  if [ -n "${ROOT_LOOP_DEV}" ]
-  then
-    sudo umount "${ROOT_FS_DIR}/var"
-    cleanup_loop "${ROOT_LOOP_DEV}"
+# Emerges chromeos-test onto the image.
+emerge_chromeos_test() {
+  INSTALL_MASK=""
+  if [[ $FLAGS_installmask -eq ${FLAGS_TRUE} ]]; then
+    INSTALL_MASK="$DEFAULT_INSTALL_MASK"
   fi
-  rmdir "${ROOT_FS_DIR}"
 
-  cleanup_mounts "${STATEFUL_DIR}"
-  if [ -n "${STATEFUL_LOOP_DEV}" ]
-  then
-    cleanup_loop "${STATEFUL_LOOP_DEV}"
-  fi
-  rmdir "${STATEFUL_DIR}"
+  # Determine the root dir for test packages.
+  ROOT_DEV_DIR="$ROOT_FS_DIR/usr/local"
 
-  # Turn die on error back on.
-  set -e
+  INSTALL_MASK="$INSTALL_MASK" emerge-${FLAGS_board} \
+    --root="$ROOT_DEV_DIR" --root-deps=rdeps \
+    --usepkgonly chromeos-test $EMERGE_JOBS
 }
 
 # main process begins here.
@@ -107,38 +107,19 @@ fi
 
 set -e
 
-ROOT_FS_DIR=$(dirname "${FLAGS_image}")/rootfs
-mkdir -p "${ROOT_FS_DIR}"
-
-STATEFUL_DIR=$(dirname "${FLAGS_image}")/stateful_partition
-mkdir -p "${STATEFUL_DIR}"
+IMAGE_DIR="$(dirname "$FLAGS_image")"
+IMAGE_NAME="$(basename "$FLAGS_image")"
+ROOT_FS_DIR="$IMAGE_DIR/rootfs"
+STATEFUL_DIR="$IMAGE_DIR/stateful_partition"
+SCRIPTS_DIR=$(dirname "$0")
 
 trap cleanup EXIT
 
-# Figure out how to loop mount the rootfs partition. It should be partition 3
-# on the disk image.
-offset=$(partoffset "${FLAGS_image}" 3)
+# Mounts gpt image and sets up var, /usr/local and symlinks.
+"$SCRIPTS_DIR/mount_gpt_image.sh" -i "$IMAGE_NAME" -f "$IMAGE_DIR" \
+  -r "$ROOT_FS_DIR" -s "$STATEFUL_DIR"
 
-ROOT_LOOP_DEV=$(sudo losetup -f)
-if [ -z "$ROOT_LOOP_DEV" ]; then
-  echo "No free loop device"
-  exit 1
-fi
-sudo losetup -o $(( $offset * 512 )) "${ROOT_LOOP_DEV}" "${FLAGS_image}"
-sudo mount "${ROOT_LOOP_DEV}" "${ROOT_FS_DIR}"
-
-# The stateful partition should be partition 1 on the disk image.
-offset=$(partoffset "${FLAGS_image}" 1)
-
-STATEFUL_LOOP_DEV=$(sudo losetup -f)
-if [ -z "$STATEFUL_LOOP_DEV" ]; then
-  echo "No free loop device"
-  exit 1
-fi
-sudo losetup -o $(( $offset * 512 )) "${STATEFUL_LOOP_DEV}" "${FLAGS_image}"
-sudo mount "${STATEFUL_LOOP_DEV}" "${STATEFUL_DIR}"
-sudo mount --bind "${STATEFUL_DIR}/var" "${ROOT_FS_DIR}/var"
-STATEFUL_DIR="${STATEFUL_DIR}"
+emerge_chromeos_test
 
 MOD_TEST_ROOT="${GCLIENT_ROOT}/src/scripts/mod_for_test_scripts"
 # Run test setup script to modify the image
@@ -159,7 +140,7 @@ if [ ${FLAGS_factory_install} -eq ${FLAGS_TRUE} ]; then
       --root-deps=rdeps chromeos-factoryinstall
 
   # Set factory server if necessary.
-  if [ "${FACTORY_SERVER}" != "" ]; then 
+  if [ "${FACTORY_SERVER}" != "" ]; then
     sudo sed -i \
       "s/CHROMEOS_AUSERVER=.*$/CHROMEOS_AUSERVER=\
 http:\/\/${FACTORY_SERVER}:8080\/update/" \
diff --git a/mount_gpt_image.sh b/mount_gpt_image.sh
index 7d59ef4496..a739675d49 100755
--- a/mount_gpt_image.sh
+++ b/mount_gpt_image.sh
@@ -9,6 +9,9 @@
 
 . "$(dirname "$0")/common.sh"
 
+# For functions related to gpt images.
+. "$(dirname "$0")/chromeos-common.sh"
+
 get_default_board
 
 # Flags.
@@ -18,7 +21,8 @@ DEFINE_boolean unmount $FLAGS_FALSE \
   "Unmount previously mounted dir." u
 DEFINE_string from "/dev/sdc" \
   "Directory containing image or device with image on it" f
-DEFINE_boolean test $FLAGS_FALSE "Use chromiumos_test_image.bin" t
+DEFINE_string image "chromiumos_image.bin"\
+  "Name of the bin file if a directory is specified in the from flag" i
 DEFINE_string "rootfs_mountpt" "/tmp/m" "Mount point for rootfs" "r"
 DEFINE_string "stateful_mountpt" "/tmp/s" \
     "Mount point for stateful partition" "s"
@@ -31,13 +35,16 @@ eval set -- "${FLAGS_ARGV}"
 # Die on error
 set -e
 
-# Common umounts for either a device or directory
-function unmount_common() {
+# Common unmounts for either a device or directory
+function unmount_image() {
   echo "Unmounting image from ${FLAGS_stateful_mountpt}" \
       "and ${FLAGS_rootfs_mountpt}"
   # Don't die on error to force cleanup
   set +e
   if [ -e "${FLAGS_rootfs_mountpt}/root/.dev_mode" ] ; then
+    # Reset symlinks in /usr/local.
+    setup_symlinks_on_root "/usr/local" "/var" \
+      "${FLAGS_stateful_mountpt}"
     sudo umount "${FLAGS_rootfs_mountpt}/usr/local"
   fi
   sudo umount "${FLAGS_rootfs_mountpt}/var"
@@ -46,55 +53,63 @@ function unmount_common() {
   set -e
 }
 
-# Sets up the rootfs and stateful partitions specified by
-# ${FLAGS_from}${prefix}[31] to the given mount points and sets up var and
-# usr/local
-# ${1} - prefix name for the partition
-# ${2} - extra mount options for the partitions
-function mount_common() {
+function get_usb_partitions() {
+  sudo mount "${FLAGS_from}3" "${FLAGS_rootfs_mountpt}"
+  sudo mount "${FLAGS_from}1" "${FLAGS_stateful_mountpt}"
+}
+
+function get_gpt_partitions() {
+  local filename="${FLAGS_image}"
+
+  # Mount the rootfs partition using a loopback device.
+  local offset=$(partoffset "${FLAGS_from}/${filename}" 3)
+  sudo mount -o loop,offset=$(( offset * 512 )) "${FLAGS_from}/${filename}" \
+    "${FLAGS_rootfs_mountpt}"
+
+  # Mount the stateful partition using a loopback device.
+  offset=$(partoffset "${FLAGS_from}/${filename}" 1)
+  sudo mount -o loop,offset=$(( offset * 512 )) "${FLAGS_from}/${filename}" \
+    "${FLAGS_stateful_mountpt}"
+}
+
+# Mount a gpt based image.
+function mount_image() {
   mkdir -p "${FLAGS_rootfs_mountpt}"
   mkdir -p "${FLAGS_stateful_mountpt}"
-  sudo mount ${2} "${FLAGS_from}${1}3" "${FLAGS_rootfs_mountpt}"
-  sudo mount ${2} "${FLAGS_from}${1}1" "${FLAGS_stateful_mountpt}"
+
+  # Get the partitions for the image / device.
+  if [ -b ${FLAGS_from} ] ; then
+    get_usb_partitions
+  else
+    get_gpt_partitions
+  fi
+
+  # Mount var unconditionally and then setup /usr/local for user of dev mode.
   sudo mount --bind "${FLAGS_stateful_mountpt}/var" \
     "${FLAGS_rootfs_mountpt}/var"
   if [ -e "${FLAGS_rootfs_mountpt}/root/.dev_mode" ] ; then
     sudo mount --bind "${FLAGS_stateful_mountpt}/dev_image" \
       "${FLAGS_rootfs_mountpt}/usr/local"
+    # Setup symlinks in /usr/local so you can emerge packages into /usr/local.
+    setup_symlinks_on_root "${FLAGS_stateful_mountpt}/dev_image" \
+      "${FLAGS_stateful_mountpt}/var" "${FLAGS_stateful_mountpt}"
   fi
-  echo "Root FS specified by "${FLAGS_from}${1}3" mounted at"\
+  echo "Image specified by ${FLAGS_from} mounted at"\
     "${FLAGS_rootfs_mountpt} successfully."
 }
 
-# Find the last image built on the board
+# Find the last image built on the board.
 if [ ${FLAGS_most_recent} -eq ${FLAGS_TRUE} ] ; then
   IMAGES_DIR="${DEFAULT_BUILD_ROOT}/images/${FLAGS_board}"
   FLAGS_from="${IMAGES_DIR}/$(ls -t ${IMAGES_DIR} 2>&-| head -1)"
 fi
 
-# Turn into absolute path
+# Turn path into an absolute path.
 FLAGS_from=`eval readlink -f ${FLAGS_from}`
 
-# Set the file name of the image if ${FLAGS_from} is not a device and cd
-if [ -d "${FLAGS_from}" ] ; then
-  cd "${FLAGS_from}"
-  IMAGE_NAME=chromiumos_image.bin
-  [ ${FLAGS_test} -eq ${FLAGS_TRUE} ] && IMAGE_NAME=chromiumos_test_image.bin
-fi
-
+# Perform desired operation.
 if [ ${FLAGS_unmount} -eq ${FLAGS_TRUE} ] ; then
-  unmount_common
-  if [ -d "${FLAGS_from}" ] ; then
-    echo "Re-packing partitions onto ${FLAGS_from}/${IMAGE_NAME}"
-    ./pack_partitions.sh ${IMAGE_NAME} 2> /dev/null
-    sudo rm part_*
-  fi
+  unmount_image
 else
-  if [ -b ${FLAGS_from} ] ; then
-    mount_common "" ""
-  else
-    echo "Unpacking partitions from ${FLAGS_from}/${IMAGE_NAME}"
-    ./unpack_partitions.sh ${IMAGE_NAME} 2> /dev/null
-    mount_common "/part_" "-o loop"
-  fi
+  mount_image
 fi