diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 0061819..414ab97 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1339,6 +1339,35 @@
   RunAndCheckOutput(verify_cmd)
 
 
+def AppendGkiSigningArgs(cmd):
+  """Append GKI signing arguments for mkbootimg."""
+  # e.g., --gki_signing_key path/to/signing_key
+  #       --gki_signing_algorithm SHA256_RSA4096"
+
+  key_path = OPTIONS.info_dict.get("gki_signing_key_path")
+  # It's fine that a non-GKI boot.img has no gki_signing_key_path.
+  if not key_path:
+    return
+
+  if not os.path.exists(key_path) and OPTIONS.search_path:
+    new_key_path = os.path.join(OPTIONS.search_path, key_path)
+    if os.path.exists(new_key_path):
+      key_path = new_key_path
+
+  # Checks key_path exists, before appending --gki_signing_* args.
+  if not os.path.exists(key_path):
+    raise ExternalError('gki_signing_key_path: "{}" not found'.format(key_path))
+
+  algorithm = OPTIONS.info_dict.get("gki_signing_algorithm")
+  if key_path and algorithm:
+    cmd.extend(["--gki_signing_key", key_path,
+                "--gki_signing_algorithm", algorithm])
+
+    signature_args = OPTIONS.info_dict.get("gki_signing_signature_args")
+    if signature_args:
+      cmd.extend(["--gki_signing_signature_args", signature_args])
+
+
 def BuildVBMeta(image_path, partitions, name, needed_partitions):
   """Creates a VBMeta image.
 
@@ -1520,6 +1549,8 @@
   if has_ramdisk:
     cmd.extend(["--ramdisk", ramdisk_img.name])
 
+  AppendGkiSigningArgs(cmd)
+
   img_unsigned = None
   if info_dict.get("vboot"):
     img_unsigned = tempfile.NamedTemporaryFile()
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index 00acd98..3db5559 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -123,6 +123,17 @@
       mounted on the partition (e.g. "--signing_helper /path/to/helper"). The
       args will be appended to the existing ones in info dict.
 
+  --gki_signing_algorithm <algorithm>
+  --gki_signing_key <key>
+      Use the specified algorithm (e.g. SHA256_RSA4096) and the key to generate
+      'boot signature' in a v4 boot.img. Otherwise it uses the existing values
+      in info dict.
+
+  --gki_signing_extra_args <args>
+      Specify any additional args that are needed to generate 'boot signature'
+      (e.g. --prop foo:bar). The args will be appended to the existing ones
+      in info dict.
+
   --android_jar_path <path>
       Path to the android.jar to repack the apex file.
 """
@@ -174,6 +185,9 @@
 OPTIONS.avb_keys = {}
 OPTIONS.avb_algorithms = {}
 OPTIONS.avb_extra_args = {}
+OPTIONS.gki_signing_key = None
+OPTIONS.gki_signing_algorithm = None
+OPTIONS.gki_signing_extra_args = None
 OPTIONS.android_jar_path = None
 
 
@@ -677,6 +691,9 @@
   if misc_info.get('avb_enable') == 'true':
     RewriteAvbProps(misc_info)
 
+  # Replace the GKI signing key for boot.img, if any.
+  ReplaceGkiSigningKey(misc_info)
+
   # Write back misc_info with the latest values.
   ReplaceMiscInfoTxt(input_tf_zip, output_tf_zip, misc_info)
 
@@ -995,6 +1012,28 @@
       misc_info[args_key] = result
 
 
+def ReplaceGkiSigningKey(misc_info):
+  """Replaces the GKI signing key."""
+
+  key = OPTIONS.gki_signing_key
+  if not key:
+    return
+
+  algorithm = OPTIONS.gki_signing_algorithm
+  if not algorithm:
+    raise ValueError("Missing --gki_signing_algorithm")
+
+  print('Replacing GKI signing key with "%s" (%s)' % (key, algorithm))
+  misc_info["gki_signing_algorithm"] = algorithm
+  misc_info["gki_signing_key_path"] = key
+
+  extra_args = OPTIONS.gki_signing_extra_args
+  if extra_args:
+    print('Setting extra GKI signing args: "%s"' % (extra_args))
+    misc_info["gki_signing_signature_args"] = (
+        misc_info.get("gki_signing_signature_args", '') + ' ' + extra_args)
+
+
 def BuildKeyMap(misc_info, key_mapping_options):
   for s, d in key_mapping_options:
     if s is None:   # -d option
@@ -1226,6 +1265,12 @@
       # 'oem=--signing_helper_with_files=/tmp/avbsigner.sh'.
       partition, extra_args = a.split("=", 1)
       OPTIONS.avb_extra_args[partition] = extra_args
+    elif o == "--gki_signing_key":
+      OPTIONS.gki_signing_key = a
+    elif o == "--gki_signing_algorithm":
+      OPTIONS.gki_signing_algorithm = a
+    elif o == "--gki_signing_extra_args":
+      OPTIONS.gki_signing_extra_args = a
     else:
       return False
     return True
@@ -1273,6 +1318,9 @@
           "avb_extra_custom_image_key=",
           "avb_extra_custom_image_algorithm=",
           "avb_extra_custom_image_extra_args=",
+          "gki_signing_key=",
+          "gki_signing_algorithm=",
+          "gki_signing_extra_args=",
       ],
       extra_option_handler=option_handler)
 
diff --git a/tools/releasetools/test_common.py b/tools/releasetools/test_common.py
index ecd759c..a516366 100644
--- a/tools/releasetools/test_common.py
+++ b/tools/releasetools/test_common.py
@@ -1670,6 +1670,127 @@
                   common.OPTIONS.aftl_key_path]
     common.RunAndCheckOutput(verify_cmd)
 
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_AppendGkiSigningArgs_NoSigningKeyPath(self):
+    # A non-GKI boot.img has no gki_signing_key_path.
+    common.OPTIONS.info_dict = {
+        # 'gki_signing_key_path': pubkey,
+        'gki_signing_algorithm': 'SHA256_RSA4096',
+        'gki_signing_signature_args': '--prop foo:bar',
+    }
+
+    # Tests no --gki_signing_* args are appended if there is no
+    # gki_signing_key_path.
+    cmd = ['mkbootimg', '--header_version', '4']
+    expected_cmd = ['mkbootimg', '--header_version', '4']
+    common.AppendGkiSigningArgs(cmd)
+    self.assertEqual(cmd, expected_cmd)
+
+  def test_AppendGkiSigningArgs_NoSigningAlgorithm(self):
+    pubkey = os.path.join(self.testdata_dir, 'testkey_gki.pem')
+    with open(pubkey, 'wb') as f:
+      f.write(b'\x00' * 100)
+    self.assertTrue(os.path.exists(pubkey))
+
+    # Tests no --gki_signing_* args are appended if there is no
+    # gki_signing_algorithm.
+    common.OPTIONS.info_dict = {
+        'gki_signing_key_path': pubkey,
+        # 'gki_signing_algorithm': 'SHA256_RSA4096',
+        'gki_signing_signature_args': '--prop foo:bar',
+    }
+
+    cmd = ['mkbootimg', '--header_version', '4']
+    expected_cmd = ['mkbootimg', '--header_version', '4']
+    common.AppendGkiSigningArgs(cmd)
+    self.assertEqual(cmd, expected_cmd)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_AppendGkiSigningArgs(self):
+    pubkey = os.path.join(self.testdata_dir, 'testkey_gki.pem')
+    with open(pubkey, 'wb') as f:
+      f.write(b'\x00' * 100)
+    self.assertTrue(os.path.exists(pubkey))
+
+    common.OPTIONS.info_dict = {
+        'gki_signing_key_path': pubkey,
+        'gki_signing_algorithm': 'SHA256_RSA4096',
+        'gki_signing_signature_args': '--prop foo:bar',
+    }
+    cmd = ['mkbootimg', '--header_version', '4']
+    common.AppendGkiSigningArgs(cmd)
+
+    expected_cmd = [
+      'mkbootimg', '--header_version', '4',
+      '--gki_signing_key', pubkey,
+      '--gki_signing_algorithm', 'SHA256_RSA4096',
+      '--gki_signing_signature_args', '--prop foo:bar'
+    ]
+    self.assertEqual(cmd, expected_cmd)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_AppendGkiSigningArgs_KeyPathNotFound(self):
+    pubkey = os.path.join(self.testdata_dir, 'no_testkey_gki.pem')
+    self.assertFalse(os.path.exists(pubkey))
+
+    common.OPTIONS.info_dict = {
+        'gki_signing_key_path': pubkey,
+        'gki_signing_algorithm': 'SHA256_RSA4096',
+        'gki_signing_signature_args': '--prop foo:bar',
+    }
+    cmd = ['mkbootimg', '--header_version', '4']
+    self.assertRaises(common.ExternalError, common.AppendGkiSigningArgs, cmd)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_AppendGkiSigningArgs_SearchKeyPath(self):
+    pubkey = 'testkey_gki.pem'
+    self.assertFalse(os.path.exists(pubkey))
+
+    # Tests it should replace the pubkey with an existed key under
+    # OPTIONS.search_path, i.e., os.path.join(OPTIONS.search_path, pubkey).
+    search_path_dir = common.MakeTempDir()
+    search_pubkey = os.path.join(search_path_dir, pubkey)
+    with open(search_pubkey, 'wb') as f:
+      f.write(b'\x00' * 100)
+    self.assertTrue(os.path.exists(search_pubkey))
+
+    common.OPTIONS.search_path = search_path_dir
+    common.OPTIONS.info_dict = {
+        'gki_signing_key_path': pubkey,
+        'gki_signing_algorithm': 'SHA256_RSA4096',
+        'gki_signing_signature_args': '--prop foo:bar',
+    }
+    cmd = ['mkbootimg', '--header_version', '4']
+    common.AppendGkiSigningArgs(cmd)
+
+    expected_cmd = [
+      'mkbootimg', '--header_version', '4',
+      '--gki_signing_key', search_pubkey,
+      '--gki_signing_algorithm', 'SHA256_RSA4096',
+      '--gki_signing_signature_args', '--prop foo:bar'
+    ]
+    self.assertEqual(cmd, expected_cmd)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_AppendGkiSigningArgs_SearchKeyPathNotFound(self):
+    pubkey = 'no_testkey_gki.pem'
+    self.assertFalse(os.path.exists(pubkey))
+
+    # Tests it should raise ExternalError if no key found under
+    # OPTIONS.search_path.
+    search_path_dir = common.MakeTempDir()
+    search_pubkey = os.path.join(search_path_dir, pubkey)
+    self.assertFalse(os.path.exists(search_pubkey))
+
+    common.OPTIONS.search_path = search_path_dir
+    common.OPTIONS.info_dict = {
+        'gki_signing_key_path': pubkey,
+        'gki_signing_algorithm': 'SHA256_RSA4096',
+        'gki_signing_signature_args': '--prop foo:bar',
+    }
+    cmd = ['mkbootimg', '--header_version', '4']
+    self.assertRaises(common.ExternalError, common.AppendGkiSigningArgs, cmd)
+
 
 class InstallRecoveryScriptFormatTest(test_utils.ReleaseToolsTestCase):
   """Checks the format of install-recovery.sh.
diff --git a/tools/releasetools/test_sign_target_files_apks.py b/tools/releasetools/test_sign_target_files_apks.py
index 18e4858..64e27a2 100644
--- a/tools/releasetools/test_sign_target_files_apks.py
+++ b/tools/releasetools/test_sign_target_files_apks.py
@@ -23,8 +23,8 @@
 import test_utils
 from sign_target_files_apks import (
     CheckApkAndApexKeysAvailable, EditTags, GetApkFileInfo, ReadApexKeysInfo,
-    ReplaceCerts, ReplaceVerityKeyId, RewriteAvbProps, RewriteProps,
-    WriteOtacerts)
+    ReplaceCerts, ReplaceGkiSigningKey, ReplaceVerityKeyId, RewriteAvbProps,
+    RewriteProps, WriteOtacerts)
 
 
 class SignTargetFilesApksTest(test_utils.ReleaseToolsTestCase):
@@ -588,3 +588,52 @@
             'system/apex/apexd/apexd_testdata/com.android.apex.test_package_2.pem',
             'build/make/target/product/security/testkey'),
         }, keys_info)
+
+  def test_ReplaceGkiSigningKey(self):
+    common.OPTIONS.gki_signing_key = 'release_gki_key'
+    common.OPTIONS.gki_signing_algorithm = 'release_gki_algorithm'
+    common.OPTIONS.gki_signing_extra_args = 'release_gki_signature_extra_args'
+
+    misc_info = {
+        'gki_signing_key_path': 'default_gki_key',
+        'gki_signing_algorithm': 'default_gki_algorithm',
+        'gki_signing_signature_args': 'default_gki_signature_args',
+    }
+    expected_dict = {
+        'gki_signing_key_path': 'release_gki_key',
+        'gki_signing_algorithm': 'release_gki_algorithm',
+        'gki_signing_signature_args': 'default_gki_signature_args release_gki_signature_extra_args',
+    }
+    ReplaceGkiSigningKey(misc_info)
+    self.assertDictEqual(expected_dict, misc_info)
+
+  def test_ReplaceGkiSigningKey_MissingSigningAlgorithm(self):
+    common.OPTIONS.gki_signing_key = 'release_gki_key'
+    common.OPTIONS.gki_signing_algorithm = None
+    common.OPTIONS.gki_signing_extra_args = 'release_gki_signature_extra_args'
+
+    misc_info = {
+        'gki_signing_key_path': 'default_gki_key',
+        'gki_signing_algorithm': 'default_gki_algorithm',
+        'gki_signing_signature_args': 'default_gki_signature_args',
+    }
+    self.assertRaises(ValueError, ReplaceGkiSigningKey, misc_info)
+
+  def test_ReplaceGkiSigningKey_MissingSigningKeyNop(self):
+    common.OPTIONS.gki_signing_key = None
+    common.OPTIONS.gki_signing_algorithm = 'release_gki_algorithm'
+    common.OPTIONS.gki_signing_extra_args = 'release_gki_signature_extra_args'
+
+    # No change to misc_info if common.OPTIONS.gki_signing_key is missing.
+    misc_info = {
+        'gki_signing_key_path': 'default_gki_key',
+        'gki_signing_algorithm': 'default_gki_algorithm',
+        'gki_signing_signature_args': 'default_gki_signature_args',
+    }
+    expected_dict = {
+        'gki_signing_key_path': 'default_gki_key',
+        'gki_signing_algorithm': 'default_gki_algorithm',
+        'gki_signing_signature_args': 'default_gki_signature_args',
+    }
+    ReplaceGkiSigningKey(misc_info)
+    self.assertDictEqual(expected_dict, misc_info)