diff --git a/cr-buildbucket.cfg b/cr-buildbucket.cfg
index 7ff338aa1..e8ec58297 100644
--- a/cr-buildbucket.cfg
+++ b/cr-buildbucket.cfg
@@ -32,6 +32,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -55,6 +59,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -78,6 +86,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -99,6 +111,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -120,6 +136,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -141,6 +161,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -164,6 +188,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -187,6 +215,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -210,6 +242,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -233,6 +269,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -256,6 +296,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -279,6 +323,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -302,6 +350,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -325,6 +377,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -348,6 +404,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -371,6 +431,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -394,6 +458,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -416,6 +484,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -438,6 +510,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -460,6 +536,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -483,6 +563,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -506,6 +590,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -529,6 +617,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -552,6 +644,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -575,6 +671,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -598,6 +698,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -621,6 +725,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -644,6 +752,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -666,6 +778,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -688,6 +804,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -710,6 +830,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -732,6 +856,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -764,6 +892,10 @@ buckets {
       execution_timeout_secs: 7200
       build_numbers: YES
       service_account: "libyuv-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -805,6 +937,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -826,6 +962,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -847,6 +987,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -870,6 +1014,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -893,6 +1041,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -915,6 +1067,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -937,6 +1093,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -959,6 +1119,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -981,6 +1145,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1004,6 +1172,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1027,6 +1199,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1050,6 +1226,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1073,6 +1253,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1096,6 +1280,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1119,6 +1307,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1142,6 +1334,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1165,6 +1361,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1187,6 +1387,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1209,6 +1413,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1231,6 +1439,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1256,6 +1468,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1279,6 +1495,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1302,6 +1522,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1325,6 +1549,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1348,6 +1576,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1371,6 +1603,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
@@ -1394,6 +1630,10 @@ buckets {
       execution_timeout_secs: 10800
       build_numbers: YES
       service_account: "libyuv-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
       experiments {
         key: "luci.use_realms"
         value: 100
diff --git a/main.star b/main.star
index d4cec7fe5..610281920 100755
--- a/main.star
+++ b/main.star
@@ -29,7 +29,12 @@ GOMA_BACKEND_RBE_NO_ATS_PROD = {
 # Enable LUCI Realms support.
 lucicfg.enable_experiment("crbug.com/1085650")
 # Launch all builds in "realms-aware mode", crbug.com/1203285.
-luci.builder.defaults.experiments.set({"luci.use_realms": 100})
+luci.builder.defaults.experiments.set(
+    {
+        "luci.use_realms": 100,
+        "luci.recipes.use_python3": 100,
+    },
+)
 
 lucicfg.config(
     lint_checks = ["default"],