diff --git a/benches/fibonacci.rs b/benches/fibonacci.rs
index 1f8a2aafc9e..39974ad6c18 100644
--- a/benches/fibonacci.rs
+++ b/benches/fibonacci.rs
@@ -1,11 +1,9 @@
-#![feature(custom_attribute, test)]
-#![feature(rustc_private)]
-#![allow(unused_attributes)]
+#![feature(test, rustc_private)]
 
 extern crate test;
 use test::Bencher;
-
-mod fibonacci_helper;
+mod helpers;
+use helpers::*;
 
 #[bench]
 fn fib(bencher: &mut Bencher) {
@@ -14,15 +12,11 @@ fn fib(bencher: &mut Bencher) {
     })
 }
 
-mod miri_helper;
-
 #[bench]
 fn fib_miri(bencher: &mut Bencher) {
     miri_helper::run("fibonacci_helper", bencher);
 }
 
-mod fibonacci_helper_iterative;
-
 #[bench]
 fn fib_iter(bencher: &mut Bencher) {
     bencher.iter(|| {
diff --git a/benches/fibonacci_helper.rs b/benches/helpers/fibonacci_helper.rs
similarity index 100%
rename from benches/fibonacci_helper.rs
rename to benches/helpers/fibonacci_helper.rs
diff --git a/benches/fibonacci_helper_iterative.rs b/benches/helpers/fibonacci_helper_iterative.rs
similarity index 100%
rename from benches/fibonacci_helper_iterative.rs
rename to benches/helpers/fibonacci_helper_iterative.rs
diff --git a/benches/miri_helper.rs b/benches/helpers/miri_helper.rs
similarity index 93%
rename from benches/miri_helper.rs
rename to benches/helpers/miri_helper.rs
index 1b4b14c427f..c8ae22e1ace 100644
--- a/benches/miri_helper.rs
+++ b/benches/helpers/miri_helper.rs
@@ -1,7 +1,3 @@
-#![feature(custom_attribute, test)]
-#![feature(rustc_private)]
-#![allow(unused_attributes)]
-
 extern crate getopts;
 extern crate miri;
 extern crate rustc;
@@ -32,7 +28,7 @@ fn find_sysroot() -> String {
 pub fn run(filename: &str, bencher: &mut Bencher) {
     let args = &[
         "miri".to_string(),
-        format!("benches/{}.rs", filename),
+        format!("benches/helpers/{}.rs", filename),
         "--sysroot".to_string(),
         find_sysroot()
     ];
diff --git a/benches/helpers/mod.rs b/benches/helpers/mod.rs
new file mode 100644
index 00000000000..27504a2cc03
--- /dev/null
+++ b/benches/helpers/mod.rs
@@ -0,0 +1,7 @@
+// This module gets included in multiple crates, and they each only use part of it.
+#![allow(dead_code)]
+
+pub mod fibonacci_helper;
+pub mod fibonacci_helper_iterative;
+pub mod miri_helper;
+pub mod smoke_helper;
diff --git a/benches/smoke_helper.rs b/benches/helpers/smoke_helper.rs
similarity index 100%
rename from benches/smoke_helper.rs
rename to benches/helpers/smoke_helper.rs
diff --git a/benches/smoke.rs b/benches/smoke.rs
index 43baf486df3..eabd58a8688 100644
--- a/benches/smoke.rs
+++ b/benches/smoke.rs
@@ -1,11 +1,9 @@
-#![feature(custom_attribute, test)]
-#![feature(rustc_private)]
-#![allow(unused_attributes)]
+#![feature(test, rustc_private)]
 
 extern crate test;
 use test::Bencher;
-
-mod smoke_helper;
+mod helpers;
+use helpers::*;
 
 #[bench]
 fn noop(bencher: &mut Bencher) {
@@ -33,8 +31,6 @@ fn noop_miri_full(bencher: &mut Bencher) {
 }
 */
 
-mod miri_helper;
-
 #[bench]
 fn noop_miri_interpreter(bencher: &mut Bencher) {
     miri_helper::run("smoke_helper", bencher);