diff --git a/build_image b/build_image
index 1068d209c4..1109b6eb9d 100755
--- a/build_image
+++ b/build_image
@@ -89,6 +89,7 @@ OVERLAY_CHROMEOS_DIR="${SRC_ROOT}/third_party/chromiumos-overlay/chromeos"
 
 . "${BUILD_LIBRARY_DIR}/board_options.sh" || exit 1
 . "${BUILD_LIBRARY_DIR}/build_gpt.sh" || exit 1
+. "${BUILD_LIBRARY_DIR}/mount_gpt_util.sh" || exit 1
 . "${BUILD_LIBRARY_DIR}/test_image_content.sh" || exit 1
 
 
@@ -288,7 +289,7 @@ cleanup_stateful_fs_loop() {
   sudo umount -d "${STATEFUL_FS_DIR}"
 }
 
-cleanup() {
+loopback_cleanup() {
   # Disable die on error.
   set +e
 
@@ -327,18 +328,6 @@ delete_prompt() {
   fi
 }
 
-# $1 - Directory where developer rootfs is mounted.
-# $2 - Directory where developer stateful_partition is mounted.
-# $3 - Directory where the ESP partition is mounted.
-mount_gpt_cleanup() {
-  local rootfs="${1-$ROOT_FS_DIR}"
-  local statefs="${2-$STATEFUL_FS_DIR}"
-  local espfs="${3-$ESP_FS_DIR}"
-  "${SCRIPTS_DIR}/mount_gpt_image.sh" \
-    -u -r "${rootfs}" -s "${statefs}" -e "${espfs}"
-  delete_prompt
-}
-
 # Takes no arguments and populates the configuration for
 # cros_make_image_bootable.
 create_boot_desc() {
@@ -368,11 +357,10 @@ install_dev_packages() {
 
   echo "Adding developer packages to ${image_name}"
 
-  trap "mount_gpt_cleanup" EXIT
+  trap "unmount_image ; delete_prompt" EXIT
 
-  ${SCRIPTS_DIR}/mount_gpt_image.sh --from "${OUTPUT_DIR}" \
-    --image "${image_name}" -r "${ROOT_FS_DIR}" \
-    -s "${STATEFUL_FS_DIR}" -e "${ESP_FS_DIR}"
+  mount_image "${OUTPUT_DIR}/${image_name}" "${ROOT_FS_DIR}" \
+    "${STATEFUL_FS_DIR}" "${ESP_FS_DIR}"
 
   # Determine the root dir for developer packages.
   local root_dev_dir="${ROOT_FS_DIR}"
@@ -445,9 +433,8 @@ install_dev_packages() {
   fi
   echo "Developer image built and stored at ${image_name}"
 
+  unmount_image
   trap - EXIT
-  ${SCRIPTS_DIR}/mount_gpt_image.sh -u -r "${ROOT_FS_DIR}" \
-    -s "${STATEFUL_FS_DIR}" -e "${ESP_FS_DIR}"
 }
 
 zero_free_space() {
@@ -462,7 +449,7 @@ zero_free_space() {
 create_base_image() {
   local image_name=$1
 
-  trap "cleanup && delete_prompt" EXIT
+  trap "loopback_cleanup && delete_prompt" EXIT
 
   # Create and format the root file system.
 
@@ -616,8 +603,7 @@ create_base_image() {
   # payloads become smaller
   zero_free_space "${ROOT_FS_DIR}"
 
-  cleanup
-
+  loopback_cleanup
   trap delete_prompt EXIT
 
   # Now that the filler file has been sync'd to disk and has filled up all free
@@ -647,11 +633,6 @@ generate_au_zip () {
   $lgenerateauzip $largs
 }
 
-mod_image_for_test_cleanup() {
-  "${SCRIPTS_DIR}/mount_gpt_image.sh" -u -r "${ROOT_FS_DIR}" \
-    -s "${STATEFUL_FS_DIR}"
-}
-
 # Emerges chromeos-test onto the image.
 emerge_chromeos_test() {
   # Determine the root dir for test packages.
@@ -714,11 +695,10 @@ mod_image_for_test () {
   local image_dir=$(dirname ${test_pathname})
   local image_name=$(basename ${test_pathname})
 
-  trap mod_image_for_test_cleanup EXIT
+  trap unmount_image EXIT
 
-  # 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 "${STATEFUL_FS_DIR}"
+  mount_image "${image_dir}/${image_name}" \
+    "${ROOT_FS_DIR}" "${STATEFUL_FS_DIR}"
 
   emerge_chromeos_test
 
@@ -748,15 +728,13 @@ mod_image_for_test () {
   # Re-run ldconfig to fix /etc/ldconfig.so.cache.
   sudo ldconfig -r "${ROOT_FS_DIR}"
 
-  mod_image_for_test_cleanup
+  unmount_image
+  trap - EXIT
 
   # Now make it bootable with the flags from build_image
-  "${SCRIPTS_DIR}/bin/cros_make_image_bootable" "${image_dir}" "${image_name}" \
-                                              --force_developer_mode
-
-  print_time_elapsed
-
-  trap - EXIT
+  "${SCRIPTS_DIR}/bin/cros_make_image_bootable" "${image_dir}" \
+                                                "${image_name}" \
+                                                --force_developer_mode
 }
 
 # Create the output directory.
diff --git a/build_library/mount_gpt_util.sh b/build_library/mount_gpt_util.sh
new file mode 100755
index 0000000000..bf83e281c3
--- /dev/null
+++ b/build_library/mount_gpt_util.sh
@@ -0,0 +1,35 @@
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This global array variable is used to remember options from
+# mount_image so that unmount_image can do its job.
+MOUNT_GPT_OPTIONS=( )
+
+# mount_image - Mount the root, stateful, and optionally ESP partitions
+#   in a Chromium OS image.
+# $1: path to image to be mounted
+# $2: path to root fs mount point
+# $3: path to stateful fs mount point
+# $4: path to ESP fs mount point; if empty the ESP will not be mounted
+mount_image() {
+  local image_dir="$(dirname $1)"
+  local image="$(basename $1)"
+  MOUNT_GPT_OPTIONS=( -r "$2" -s "$3" )
+
+  if [ $# -ge 4 ]; then
+    MOUNT_GPT_OPTIONS=( "${MOUNT_GPT_OPTIONS[@]}" -e "$4" )
+  fi
+
+  "${SCRIPTS_DIR}/mount_gpt_image.sh" --from="$image_dir" --image="$image" \
+    "${MOUNT_GPT_OPTIONS[@]}"
+}
+
+# unmount_image - Unmount the file systems mounted in the previous
+#   call to mount_image.
+# No arguments
+unmount_image() {
+  "${SCRIPTS_DIR}/mount_gpt_image.sh" -u "${MOUNT_GPT_OPTIONS[@]}"
+
+  MOUNT_GPT_OPTIONS=( )
+}
diff --git a/mod_image_for_test.sh b/mod_image_for_test.sh
index f08377ebe4..348bd9bbe6 100755
--- a/mod_image_for_test.sh
+++ b/mod_image_for_test.sh
@@ -53,7 +53,8 @@ eval set -- "$FLAGS_ARGV"
 # so will die prematurely if 'set -e' is specified before now.
 set -e
 
-. "${SCRIPT_ROOT}/build_library/board_options.sh" || exit 1
+. "${BUILD_LIBRARY_DIR}/board_options.sh" || exit 1
+. "${BUILD_LIBRARY_DIR}/mount_gpt_util.sh" || exit 1
 
 
 EMERGE_BOARD_CMD="emerge-$BOARD"
@@ -76,23 +77,6 @@ fi
 # Turn path into an absolute path.
 FLAGS_image=$(eval readlink -f "$FLAGS_image")
 
-# Make sure anything mounted in the rootfs/stateful is cleaned up ok on exit.
-cleanup_mounts() {
-  # Occasionally there are some daemons left hanging around that have our
-  # root/stateful image file system open. We do a best effort attempt to kill
-  # them.
-  PIDS=$(sudo lsof -t "$1" | sort | uniq)
-  for pid in $PIDS; do
-    local cmdline=$(cat /proc/$pid/cmdline)
-    echo "Killing process that has open file on the mounted directory: $cmdline"
-    sudo kill $pid || true
-  done
-}
-
-cleanup() {
-  "$SCRIPTS_DIR/mount_gpt_image.sh" -u -r "$ROOT_FS_DIR" -s "$STATEFUL_DIR"
-}
-
 # Emerges chromeos-test onto the image.
 emerge_chromeos_test() {
   INSTALL_MASK=""
@@ -190,11 +174,10 @@ IMAGE_NAME=$(basename "$FLAGS_image")
 ROOT_FS_DIR="$IMAGE_DIR/rootfs"
 STATEFUL_DIR="$IMAGE_DIR/stateful_partition"
 
-trap cleanup EXIT
+trap unmount_image EXIT
 
 # 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 "$STATEFUL_DIR"
+mount_image "$FLAGS_image" "$ROOT_FS_DIR" "$STATEFUL_DIR"
 
 emerge_chromeos_test
 
@@ -231,14 +214,11 @@ if [ "$VERIFY" = "true" ]; then
   popd
 fi
 
-cleanup
+unmount_image
+trap - EXIT
 
 # Now make it bootable with the flags from build_image
 "$SCRIPTS_DIR/bin/cros_make_image_bootable" "$(dirname "$FLAGS_image")" \
                                             "$(basename "$FLAGS_image")" \
                                             --force_developer_mode
-
-
 print_time_elapsed
-
-trap - EXIT