diff --git a/BUCK b/BUCK
index d2d6d62..000b799 100644
--- a/BUCK
+++ b/BUCK
@@ -9898,6 +9898,7 @@ rust_bootstrap_library(
     crate_root = "rust/compiler/rustc_interface/src/lib.rs",
     edition = "2024",
     env = {
+        "CFG_DEFAULT_CODEGEN_BACKEND": "llvm",
         "RUSTC_INSTALL_BINDIR": "bin",
     },
     features = ["llvm"],
diff --git a/fixups/rustc_interface/fixups.toml b/fixups/rustc_interface/fixups.toml
index 78fc547..013a7ff 100644
--- a/fixups/rustc_interface/fixups.toml
+++ b/fixups/rustc_interface/fixups.toml
@@ -1,2 +1,3 @@
 [env]
+CFG_DEFAULT_CODEGEN_BACKEND = "llvm"
 RUSTC_INSTALL_BINDIR = "bin"