diff --git a/src/librustc/build.rs b/src/librustc/build.rs
new file mode 100644
index 00000000000..4df5f0e6405
--- /dev/null
+++ b/src/librustc/build.rs
@@ -0,0 +1,15 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_LIBDIR_RELATIVE");
+    println!("cargo:rerun-if-env-changed=CFG_COMPILER_HOST_TRIPLE");
+}
diff --git a/src/librustc_back/build.rs b/src/librustc_back/build.rs
new file mode 100644
index 00000000000..16f0872b25a
--- /dev/null
+++ b/src/librustc_back/build.rs
@@ -0,0 +1,15 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_DEFAULT_LINKER");
+    println!("cargo:rerun-if-env-changed=CFG_DEFAULT_AR");
+}
diff --git a/src/librustc_driver/build.rs b/src/librustc_driver/build.rs
new file mode 100644
index 00000000000..9844f3b557a
--- /dev/null
+++ b/src/librustc_driver/build.rs
@@ -0,0 +1,17 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_RELEASE");
+    println!("cargo:rerun-if-env-changed=CFG_VERSION");
+    println!("cargo:rerun-if-env-changed=CFG_VER_DATE");
+    println!("cargo:rerun-if-env-changed=CFG_VER_HASH");
+}
diff --git a/src/librustc_incremental/build.rs b/src/librustc_incremental/build.rs
new file mode 100644
index 00000000000..f18a3f9b940
--- /dev/null
+++ b/src/librustc_incremental/build.rs
@@ -0,0 +1,14 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_VERSION");
+}
diff --git a/src/librustc_metadata/build.rs b/src/librustc_metadata/build.rs
new file mode 100644
index 00000000000..f18a3f9b940
--- /dev/null
+++ b/src/librustc_metadata/build.rs
@@ -0,0 +1,14 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_VERSION");
+}
diff --git a/src/librustc_trans/build.rs b/src/librustc_trans/build.rs
new file mode 100644
index 00000000000..97accbb4b8f
--- /dev/null
+++ b/src/librustc_trans/build.rs
@@ -0,0 +1,16 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_VERSION");
+    println!("cargo:rerun-if-env-changed=CFG_PREFIX");
+    println!("cargo:rerun-if-env-changed=CFG_LLVM_ROOT");
+}
diff --git a/src/libsyntax/build.rs b/src/libsyntax/build.rs
new file mode 100644
index 00000000000..d39340c3326
--- /dev/null
+++ b/src/libsyntax/build.rs
@@ -0,0 +1,15 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-env-changed=CFG_RELEASE_CHANNEL");
+    println!("cargo:rerun-if-env-changed=CFG_DISABLE_UNSTABLE_FEATURES");
+}