diff --git a/libwvdrmengine/Android.bp b/libwvdrmengine/Android.bp
index 1e0c5840..4e21fc5f 100644
--- a/libwvdrmengine/Android.bp
+++ b/libwvdrmengine/Android.bp
@@ -387,21 +387,24 @@ python_binary_host {
 
 genrule {
     name: "wv_android_build_id",
+    srcs: ["version.txt"],
     tools: ["wv-android-genrule"],
-    cmd: "$(location wv-android-genrule) build_id_header > $(out)",
+    cmd: "$(location wv-android-genrule) build_id_header $(in) > $(out)",
     out: ["wv_android_build_id.h"],
 }
 
 genrule {
     name: "widevine_apex_manifest.json",
+    srcs: ["version.txt"],
     tools: ["wv-android-genrule"],
-    cmd: "$(location wv-android-genrule) apex_manifest > $(out)",
+    cmd: "$(location wv-android-genrule) apex_manifest $(in) > $(out)",
     out: ["gen_wv_apex_manifest.json"],
 }
 
 genrule {
     name: "widevine_lazy_apex_manifest.json",
+    srcs: ["version.txt"],
     tools: ["wv-android-genrule"],
-    cmd: "$(location wv-android-genrule) apex_manifest --name com.google.android.widevine.lazy > $(out)",
+    cmd: "$(location wv-android-genrule) apex_manifest --name com.google.android.widevine.lazy $(in) > $(out)",
     out: ["gen_wv_lazy_apex_manifest.json"],
 }
diff --git a/libwvdrmengine/version.txt b/libwvdrmengine/version.txt
new file mode 100644
index 00000000..e5cdc043
--- /dev/null
+++ b/libwvdrmengine/version.txt
@@ -0,0 +1 @@
+MAIN
diff --git a/libwvdrmengine/wv-android-genrule.py b/libwvdrmengine/wv-android-genrule.py
index f1f28d1c..7dcb66c1 100644
--- a/libwvdrmengine/wv-android-genrule.py
+++ b/libwvdrmengine/wv-android-genrule.py
@@ -5,30 +5,12 @@ import os
 import re
 import sys
 
-INT32_MAX = 2 ** 31 - 1
+CDM_MAJOR = 19
+CDM_MINOR = 0
 
-def guess_build_top():
-    if 'ANDROID_BUILD_TOP' in os.environ:
-        return os.environ['ANDROID_BUILD_TOP']
-    cwd = os.getcwd()
-    parts = cwd.split('/out/soong/')
-    return parts[0]
-
-
-def get_build_number():
-    top = guess_build_top()
-    with open(f'{top}/out/soong/build_number.txt', 'r') as file:
-        soong_build_number = file.read().strip()
-        return soong_build_number
-
-
-def get_build_id():
-    top = guess_build_top()
-    with open(f'{top}/build/core/build_id.mk', 'r') as file:
-        for line in file:
-            if line.startswith('BUILD_ID='):
-                _, rc = line.strip().split('=', 1)
-                return rc
+def get_build_id(args):
+    with args.version_txt as file:
+        return file.read().strip()
 
 
 def hdr(args):
@@ -36,59 +18,19 @@ def hdr(args):
 #ifndef {args.guard}
 #define {args.guard}
 
-#define WV_ANDROID_BUILD_ID "{get_build_id()}"
+#define WV_ANDROID_BUILD_ID "{get_build_id(args)}"
 
 #endif  // {args.guard}'''
     print(output)
 
 
-def safe_int(str_value):
-    """Converts a build number to an integer, capped at INT32_MAX.
-
-    INT32_MAX is the max supported by Android Build.
-
-    Args:
-        str_value: The build number to convert.
-
-    Returns:
-        The integer representation of build number, capped at INT32_MAX;
-        0 on error.
-    """
-    try:
-        v = int(str_value)
-        return min(INT32_MAX, v)
-    except ValueError:
-        return 0
-
-
 def apex_manifest(args):
-    rc = get_build_id()
-    v = get_build_number()
-
-    if v.startswith('eng.'):
-        # local build
-        #
-        # set large version so local builds can overwrite other build types
-        v = INT32_MAX
-    elif re.match(r'P\d+$', v):
-        # presubmit build
-        #
-        # numeric value of presubmit builds are typically higher than
-        # postsubmit builds, so presubmit builds can overwrite postsubmit
-        # builds during test
-        v = safe_int(v[1:])
-    elif rc in ('MASTER', 'MAIN'):
-        # postsubmit dev branch
-        #
-        # set APEX version to 1 (preserve udc behavior)
-        v = 1
-    elif re.match(r'\d+$', v):
-        # postsubmit release branch
-        #
-        # set APEX version to ab build number
-        v = safe_int(v)
+    rc = get_build_id(args)
+    m = re.match(r'[A-Z0-9]{4}\.(?P<build_date>\d{6})\.', rc)
+    if m:
+        v = int(f'{CDM_MAJOR}{CDM_MINOR}{m["build_date"]}')
     else:
-        raise RuntimeError('Unsupported Widevine APEX build env')
+        v = 1
 
     out = dict(name=args.name, version=v, requireNativeLibs=['liboemcrypto.so'])
     print(json.dumps(out))
@@ -104,12 +46,20 @@ if __name__ == '__main__':
     parser_hdr.add_argument('--guard', type=str,
                             default='WVCDM_WV_ANDROID_BUILD_ID_H_',
                             help='Include guard')
+    parser_hdr.add_argument('version_txt', type=argparse.FileType('r'),
+                            nargs='?',
+                            default=sys.stdin,
+                            help='version.txt file')
     parser_hdr.set_defaults(func=hdr)
 
     apex_description = 'Generate APEX manifest json (stdout)'
     parser_apex = subparsers.add_parser('apex_manifest', help=apex_description)
     parser_apex.add_argument('--name', help='apex name',
                              default='com.google.android.widevine')
+    parser_apex.add_argument('version_txt', type=argparse.FileType('r'),
+                             nargs='?',
+                             default=sys.stdin,
+                             help='version.txt file')
     parser_apex.set_defaults(func=apex_manifest)
 
     # Parse the arguments and call the appropriate function