diff --git a/src/build_helper/lib.rs b/src/build_helper/lib.rs
index e5c85ddb3a9..2f9953330f4 100644
--- a/src/build_helper/lib.rs
+++ b/src/build_helper/lib.rs
@@ -8,12 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-
 use std::fs::File;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
-use std::{fs, env};
 use std::time::{SystemTime, UNIX_EPOCH};
+use std::{env, fs};
 
 /// A helper macro to `unwrap` a result except also print out details like:
 ///
@@ -25,10 +24,12 @@ use std::time::{SystemTime, UNIX_EPOCH};
 /// using a `Result` with `try!`, but this may change one day...
 #[macro_export]
 macro_rules! t {
-    ($e:expr) => (match $e {
-        Ok(e) => e,
-        Err(e) => panic!("{} failed with {}", stringify!($e), e),
-    })
+    ($e:expr) => {
+        match $e {
+            Ok(e) => e,
+            Err(e) => panic!("{} failed with {}", stringify!($e), e),
+        }
+    };
 }
 
 pub fn run(cmd: &mut Command) {
@@ -45,14 +46,17 @@ pub fn run_silent(cmd: &mut Command) {
 pub fn try_run_silent(cmd: &mut Command) -> bool {
     let status = match cmd.status() {
         Ok(status) => status,
-        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}",
-                                cmd, e)),
+        Err(e) => fail(&format!(
+            "failed to execute command: {:?}\nerror: {}",
+            cmd, e
+        )),
     };
     if !status.success() {
-        println!("\n\ncommand did not execute successfully: {:?}\n\
-                  expected success, got: {}\n\n",
-                 cmd,
-                 status);
+        println!(
+            "\n\ncommand did not execute successfully: {:?}\n\
+             expected success, got: {}\n\n",
+            cmd, status
+        );
     }
     status.success()
 }
@@ -66,18 +70,22 @@ pub fn run_suppressed(cmd: &mut Command) {
 pub fn try_run_suppressed(cmd: &mut Command) -> bool {
     let output = match cmd.output() {
         Ok(status) => status,
-        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}",
-                                cmd, e)),
+        Err(e) => fail(&format!(
+            "failed to execute command: {:?}\nerror: {}",
+            cmd, e
+        )),
     };
     if !output.status.success() {
-        println!("\n\ncommand did not execute successfully: {:?}\n\
-                  expected success, got: {}\n\n\
-                  stdout ----\n{}\n\
-                  stderr ----\n{}\n\n",
-                 cmd,
-                 output.status,
-                 String::from_utf8_lossy(&output.stdout),
-                 String::from_utf8_lossy(&output.stderr));
+        println!(
+            "\n\ncommand did not execute successfully: {:?}\n\
+             expected success, got: {}\n\n\
+             stdout ----\n{}\n\
+             stderr ----\n{}\n\n",
+            cmd,
+            output.status,
+            String::from_utf8_lossy(&output.stdout),
+            String::from_utf8_lossy(&output.stderr)
+        );
     }
     output.status.success()
 }
@@ -93,9 +101,9 @@ pub fn gnu_target(target: &str) -> String {
 }
 
 pub fn make(host: &str) -> PathBuf {
-    if host.contains("bitrig") || host.contains("dragonfly") ||
-        host.contains("freebsd") || host.contains("netbsd") ||
-        host.contains("openbsd") {
+    if host.contains("bitrig") || host.contains("dragonfly") || host.contains("freebsd")
+        || host.contains("netbsd") || host.contains("openbsd")
+    {
         PathBuf::from("gmake")
     } else {
         PathBuf::from("make")
@@ -105,23 +113,27 @@ pub fn make(host: &str) -> PathBuf {
 pub fn output(cmd: &mut Command) -> String {
     let output = match cmd.stderr(Stdio::inherit()).output() {
         Ok(status) => status,
-        Err(e) => fail(&format!("failed to execute command: {:?}\nerror: {}",
-                                cmd, e)),
+        Err(e) => fail(&format!(
+            "failed to execute command: {:?}\nerror: {}",
+            cmd, e
+        )),
     };
     if !output.status.success() {
-        panic!("command did not execute successfully: {:?}\n\
-                expected success, got: {}",
-               cmd,
-               output.status);
+        panic!(
+            "command did not execute successfully: {:?}\n\
+             expected success, got: {}",
+            cmd, output.status
+        );
     }
     String::from_utf8(output.stdout).unwrap()
 }
 
 pub fn rerun_if_changed_anything_in_dir(dir: &Path) {
-    let mut stack = dir.read_dir().unwrap()
-                       .map(|e| e.unwrap())
-                       .filter(|e| &*e.file_name() != ".git")
-                       .collect::<Vec<_>>();
+    let mut stack = dir.read_dir()
+        .unwrap()
+        .map(|e| e.unwrap())
+        .filter(|e| &*e.file_name() != ".git")
+        .collect::<Vec<_>>();
     while let Some(entry) = stack.pop() {
         let path = entry.path();
         if entry.file_type().unwrap().is_dir() {
@@ -134,7 +146,9 @@ pub fn rerun_if_changed_anything_in_dir(dir: &Path) {
 
 /// Returns the last-modified time for `path`, or zero if it doesn't exist.
 pub fn mtime(path: &Path) -> SystemTime {
-    fs::metadata(path).and_then(|f| f.modified()).unwrap_or(UNIX_EPOCH)
+    fs::metadata(path)
+        .and_then(|f| f.modified())
+        .unwrap_or(UNIX_EPOCH)
 }
 
 /// Returns whether `dst` is up to date given that the file or files in `src`
@@ -175,11 +189,12 @@ impl Drop for NativeLibBoilerplate {
 // If Err is returned, then everything is up-to-date and further build actions can be skipped.
 // Timestamps are created automatically when the result of `native_lib_boilerplate` goes out
 // of scope, so all the build actions should be completed until then.
-pub fn native_lib_boilerplate(src_name: &str,
-                              out_name: &str,
-                              link_name: &str,
-                              search_subdir: &str)
-                              -> Result<NativeLibBoilerplate, ()> {
+pub fn native_lib_boilerplate(
+    src_name: &str,
+    out_name: &str,
+    link_name: &str,
+    search_subdir: &str,
+) -> Result<NativeLibBoilerplate, ()> {
     let current_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
     let src_dir = current_dir.join("..").join(src_name);
     rerun_if_changed_anything_in_dir(&src_dir);
@@ -192,11 +207,17 @@ pub fn native_lib_boilerplate(src_name: &str,
     } else {
         println!("cargo:rustc-link-lib=static={}", link_name);
     }
-    println!("cargo:rustc-link-search=native={}", out_dir.join(search_subdir).display());
+    println!(
+        "cargo:rustc-link-search=native={}",
+        out_dir.join(search_subdir).display()
+    );
 
     let timestamp = out_dir.join("rustbuild.timestamp");
     if !up_to_date(Path::new("build.rs"), &timestamp) || !up_to_date(&src_dir, &timestamp) {
-        Ok(NativeLibBoilerplate { src_dir: src_dir, out_dir: out_dir })
+        Ok(NativeLibBoilerplate {
+            src_dir: src_dir,
+            out_dir: out_dir,
+        })
     } else {
         Err(())
     }
@@ -214,10 +235,12 @@ pub fn sanitizer_lib_boilerplate(sanitizer_name: &str) -> Result<NativeLibBoiler
         ),
         _ => return Err(()),
     };
-    native_lib_boilerplate("libcompiler_builtins/compiler-rt",
-                           sanitizer_name,
-                           &link_name,
-                           search_path)
+    native_lib_boilerplate(
+        "libcompiler_builtins/compiler-rt",
+        sanitizer_name,
+        &link_name,
+        search_path,
+    )
 }
 
 fn dir_up_to_date(src: &Path, threshold: SystemTime) -> bool {