diff --git a/config/common.mk b/config/common.mk
index a5b3532..8d17bb1 100644
--- a/config/common.mk
+++ b/config/common.mk
@@ -46,6 +46,13 @@
     vendor/lineage/prebuilt/common/bin/50-lineage.sh:system/addon.d/50-lineage.sh \
     vendor/lineage/prebuilt/common/bin/blacklist:system/addon.d/blacklist
 
+ifeq ($(AB_OTA_UPDATER),true)
+PRODUCT_COPY_FILES += \
+    vendor/lineage/prebuilt/common/bin/backuptool_ab.sh:system/bin/backuptool_ab.sh \
+    vendor/lineage/prebuilt/common/bin/backuptool_ab.functions:system/bin/backuptool_ab.functions \
+    vendor/lineage/prebuilt/common/bin/backuptool_postinstall.sh:system/bin/backuptool_postinstall.sh
+endif
+
 # Backup Services whitelist
 PRODUCT_COPY_FILES += \
     vendor/lineage/config/permissions/backup.xml:system/etc/sysconfig/backup.xml
diff --git a/prebuilt/common/bin/backuptool_ab.functions b/prebuilt/common/bin/backuptool_ab.functions
new file mode 100644
index 0000000..ffb246f
--- /dev/null
+++ b/prebuilt/common/bin/backuptool_ab.functions
@@ -0,0 +1,51 @@
+#!/system/bin/sh
+#
+# Functions for backuptool_ab.sh
+#
+
+export S=/system
+export C=/postinstall/tmp/backupdir
+export V=15.1
+export backuptool_ab=true
+
+copy_file() {
+  # toybox's cp doesn't do directories correctly for whatever reason
+  mkdir -p `dirname $2`
+
+  cp -dp "$1" "$2"
+  # symlinks don't have a context
+  if [ ! -L "$1" ]; then
+    # it is assumed that every label starts with 'u:object_r' and has no white-spaces
+    local context=`ls -Z "$1" | grep -o 'u:object_r:[^ ]*' | head -1`
+    chcon "$context" "$2"
+  fi
+}
+
+backup_file() {
+  if [ -e "$1" -o -L "$1" ]; then
+    local FILE=`basename "$1"`
+    local DIR=`dirname "$1"`
+    # dont backup any apps that have odex files, they are useless
+    if ( echo "$FILE" | grep -q "\.apk$" ) && [ -e `echo "$1" | sed -e 's/\.apk$/\.odex/'` ]; then
+      echo "Skipping odexed apk $1";
+    else
+      mkdir -p "$C/$DIR"
+      copy_file "$1" "$C/$DIR/$FILE"
+    fi
+  fi
+}
+
+restore_file() {
+  local FILE=`basename "$1"`
+  local DIR=`dirname "$1"`
+  if [ -e "$C/$DIR/$FILE" -o -L "$C/$DIR/$FILE" ]; then
+    if [ ! -d "/postinstall/$DIR" ]; then
+      mkdir -p "/postinstall/$DIR";
+    fi
+    copy_file "$C/$DIR/$FILE" "/postinstall/$1";
+    if [ -n "$2" ]; then
+      echo "Deleting obsolete file $2"
+      rm "$2";
+    fi
+  fi
+}
diff --git a/prebuilt/common/bin/backuptool_ab.sh b/prebuilt/common/bin/backuptool_ab.sh
new file mode 100755
index 0000000..26034a4
--- /dev/null
+++ b/prebuilt/common/bin/backuptool_ab.sh
@@ -0,0 +1,124 @@
+#!/system/bin/sh
+#
+# Backup and restore addon /system files
+#
+
+export S=/system
+export C=/postinstall/tmp/backupdir
+export V=15.1
+
+# Scripts in /system/addon.d expect to find backuptool.functions in /tmp
+mkdir -p /postinstall/tmp/
+cp -f /postinstall/system/bin/backuptool_ab.functions /postinstall/tmp/backuptool.functions
+
+# Preserve /system/addon.d in /tmp/addon.d
+preserve_addon_d() {
+  if [ -d /system/addon.d/ ]; then
+    mkdir -p /postinstall/tmp/addon.d/
+    cp -a /system/addon.d/* /postinstall/tmp/addon.d/
+    chmod 755 /postinstall/tmp/addon.d/*.sh
+  fi
+}
+
+# Restore /postinstall/system/addon.d from /postinstall/tmp/addon.d
+restore_addon_d() {
+  if [ -d /postinstall/tmp/addon.d/ ]; then
+    mkdir -p /postinstall/system/addon.d/
+    cp -a /postinstall/tmp/addon.d/* /postinstall/system/addon.d/
+    rm -rf /postinstall/tmp/addon.d/
+  fi
+}
+
+# Proceed only if /system is the expected major and minor version
+check_prereq() {
+# If there is no build.prop file the partition is probably empty.
+if [ ! -r /system/build.prop ]; then
+    return 0
+fi
+
+grep -q "^ro.lineage.version=$V.*" /system/etc/prop.default /system/build.prop && return 1
+
+echo "Not backing up files from incompatible version: $V"
+return 0
+}
+
+check_blacklist() {
+  if [ -f /system/addon.d/blacklist -a -d /$1/addon.d/ ]; then
+      ## Discard any known bad backup scripts
+      cd /$1/addon.d/
+      for f in *sh; do
+          [ -f $f ] || continue
+          s=$(md5sum $f | cut -c-32)
+          grep -q $s /system/addon.d/blacklist && rm -f $f
+      done
+  fi
+}
+
+check_whitelist() {
+  found=0
+  if [ -f /system/addon.d/whitelist ];then
+      ## forcefully keep any version-independent stuff
+      cd /$1/addon.d/
+      for f in *sh; do
+          s=$(md5sum $f | cut -c-32)
+          grep -q $s /system/addon.d/whitelist
+          if [ $? -eq 0 ]; then
+              found=1
+          else
+              rm -f $f
+          fi
+      done
+  fi
+  return $found
+}
+
+# Execute /system/addon.d/*.sh scripts with $1 parameter
+run_stage() {
+if [ -d /postinstall/tmp/addon.d/ ]; then
+  for script in $(find /postinstall/tmp/addon.d/ -name '*.sh' |sort -n); do
+    # we have no /sbin/sh in android, only recovery
+    # use /system/bin/sh here instead
+    sed -i '0,/#!\/sbin\/sh/{s|#!/sbin/sh|#!/system/bin/sh|}' $script
+    # we can't count on /tmp existing on an A/B device, so utilize /postinstall/tmp
+    # as a pseudo-/tmp dir
+    sed -i 's|. /tmp/backuptool.functions|. /postinstall/tmp/backuptool.functions|g' $script
+    $script $1
+  done
+fi
+}
+
+case "$1" in
+  backup)
+    mkdir -p $C
+    if check_prereq; then
+        if check_whitelist postinstall/system; then
+            exit 127
+        fi
+    fi
+    check_blacklist postinstall/system
+    preserve_addon_d
+    run_stage pre-backup
+    run_stage backup
+    run_stage post-backup
+  ;;
+  restore)
+    if check_prereq; then
+        if check_whitelist postinstall/tmp; then
+            exit 127
+        fi
+    fi
+    check_blacklist postinstall/tmp
+    run_stage pre-restore
+    run_stage restore
+    run_stage post-restore
+    restore_addon_d
+    rm -rf $C
+    rm -rf /postinstall/tmp
+    sync
+  ;;
+  *)
+    echo "Usage: $0 {backup|restore}"
+    exit 1
+esac
+
+exit 0
diff --git a/prebuilt/common/bin/backuptool_postinstall.sh b/prebuilt/common/bin/backuptool_postinstall.sh
new file mode 100755
index 0000000..eef0409
--- /dev/null
+++ b/prebuilt/common/bin/backuptool_postinstall.sh
@@ -0,0 +1,11 @@
+#!/system/bin/sh
+#
+# LineageOS A/B OTA Postinstall Script
+#
+
+/postinstall/system/bin/backuptool_ab.sh backup
+/postinstall/system/bin/backuptool_ab.sh restore
+
+sync
+
+exit 0