2 files changed, 10 insertions, 6 deletions
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index cd3558ac6a4..d22fad18406 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -1049,12 +1049,12 @@ pub fn rustc_cargo(
     // <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Internal.20lint.20for.20raw.20.60print!.60.20and.20.60println!.60.3F>.
     cargo.rustflag("-Zon-broken-pipe=kill");
 
-    // We temporarily disable linking here as part of some refactoring.
-    // This way, people can manually use -Z llvm-plugins and -C passes=enzyme for now.
-    // In a follow-up PR, we will re-enable linking here and load the pass for them.
-    //if builder.config.llvm_enzyme {
-    //    cargo.rustflag("-l").rustflag("Enzyme-19");
-    //}
+    // We want to link against registerEnzyme and in the future we want to use additional
+    // functionality from Enzyme core. For that we need to link against Enzyme.
+    // FIXME(ZuseZ4): Get the LLVM version number automatically instead of hardcoding it.
+    if builder.config.llvm_enzyme {
+        cargo.rustflag("-l").rustflag("Enzyme-19");
+    }
 
     // Building with protected visibility reduces the number of dynamic relocations needed, giving
     // us a faster startup time. However GNU ld < 2.40 will error if we try to link a shared object
@@ -1234,6 +1234,9 @@ fn rustc_llvm_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelect
     if builder.is_rust_llvm(target) {
         cargo.env("LLVM_RUSTLLVM", "1");
     }
+    if builder.config.llvm_enzyme {
+        cargo.env("LLVM_ENZYME", "1");
+    }
     let llvm::LlvmResult { llvm_config, .. } = builder.ensure(llvm::Llvm { target });
     cargo.env("LLVM_CONFIG", &llvm_config);
 
diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
index 49bf04356d5..46b98a8e7ba 100644
--- a/src/bootstrap/src/core/build_steps/llvm.rs
+++ b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -968,6 +968,7 @@ impl Step for Enzyme {
             .env("LLVM_CONFIG_REAL", &llvm_config)
             .define("LLVM_ENABLE_ASSERTIONS", "ON")
             .define("ENZYME_EXTERNAL_SHARED_LIB", "ON")
+            .define("ENZYME_RUNPASS", "ON")
             .define("LLVM_DIR", builder.llvm_out(target));
 
         cfg.build();