diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index e15304a7e6e67..bfba1a0dede24 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -398,13 +398,14 @@ def run(self, args, env=None, cwd=None):
             sys.exit(ret)
 
     def output(self, args, env=None, cwd=None):
+        default_encoding = sys.getdefaultencoding()
         proc = subprocess.Popen(args, stdout=subprocess.PIPE, env=env, cwd=cwd)
         (out, err) = proc.communicate()
         ret = proc.wait()
         if ret != 0:
             print(out)
             sys.exit(ret)
-        return out
+        return out.decode(default_encoding)
 
     def build_triple(self):
         default_encoding = sys.getdefaultencoding()
@@ -570,10 +571,10 @@ def update_submodules(self):
 
         for submod in submodules:
             path, status = submod
-            if path.endswith(b"llvm") and \
+            if path.endswith('llvm') and \
                 (self.get_toml('llvm-config') or self.get_mk('CFG_LLVM_ROOT')):
                 continue
-            if path.endswith(b"jemalloc") and \
+            if path.endswith('jemalloc') and \
                 (self.get_toml('jemalloc') or self.get_mk('CFG_JEMALLOC_ROOT')):
                 continue
             submod_path = os.path.join(self.rust_root, path)
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 0fb597564e33d..abad216d89be4 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -94,6 +94,7 @@ pub struct Config {
     pub backtrace: bool, // support for RUST_BACKTRACE
 
     // misc
+    pub low_priority: bool,
     pub channel: String,
     pub quiet_tests: bool,
     // Fallback musl-root for all targets
@@ -148,6 +149,7 @@ struct Build {
     target: Vec<String>,
     cargo: Option<String>,
     rustc: Option<String>,
+    low_priority: Option<bool>,
     compiler_docs: Option<bool>,
     docs: Option<bool>,
     submodules: Option<bool>,
@@ -306,6 +308,7 @@ impl Config {
         config.nodejs = build.nodejs.map(PathBuf::from);
         config.gdb = build.gdb.map(PathBuf::from);
         config.python = build.python.map(PathBuf::from);
+        set(&mut config.low_priority, build.low_priority);
         set(&mut config.compiler_docs, build.compiler_docs);
         set(&mut config.docs, build.docs);
         set(&mut config.submodules, build.submodules);
diff --git a/src/bootstrap/config.toml.example b/src/bootstrap/config.toml.example
index df180be4e27ab..95cca96f7fcc0 100644
--- a/src/bootstrap/config.toml.example
+++ b/src/bootstrap/config.toml.example
@@ -152,6 +152,10 @@
 # known-good version of OpenSSL, compile it, and link it to Cargo.
 #openssl-static = false
 
+# Run the build with low priority, by setting the process group's "nice" value
+# to +10 on Unix platforms, and by using a "low priority" job object on Windows.
+#low-priority = false
+
 # =============================================================================
 # General install configuration options
 # =============================================================================
diff --git a/src/bootstrap/install.rs b/src/bootstrap/install.rs
index 386b001971bad..dce0b1670e181 100644
--- a/src/bootstrap/install.rs
+++ b/src/bootstrap/install.rs
@@ -21,83 +21,110 @@ use std::process::Command;
 use Build;
 use dist::{sanitize_sh, tmpdir};
 
-/// Installs everything.
-pub fn install(build: &Build, stage: u32, host: &str) {
-    let prefix_default = PathBuf::from("/usr/local");
-    let sysconfdir_default = PathBuf::from("/etc");
-    let docdir_default = PathBuf::from("share/doc/rust");
-    let bindir_default = PathBuf::from("bin");
-    let libdir_default = PathBuf::from("lib");
-    let mandir_default = PathBuf::from("share/man");
-    let prefix = build.config.prefix.as_ref().unwrap_or(&prefix_default);
-    let sysconfdir = build.config.sysconfdir.as_ref().unwrap_or(&sysconfdir_default);
-    let docdir = build.config.docdir.as_ref().unwrap_or(&docdir_default);
-    let bindir = build.config.bindir.as_ref().unwrap_or(&bindir_default);
-    let libdir = build.config.libdir.as_ref().unwrap_or(&libdir_default);
-    let mandir = build.config.mandir.as_ref().unwrap_or(&mandir_default);
-
-    let sysconfdir = prefix.join(sysconfdir);
-    let docdir = prefix.join(docdir);
-    let bindir = prefix.join(bindir);
-    let libdir = prefix.join(libdir);
-    let mandir = prefix.join(mandir);
-
-    let destdir = env::var_os("DESTDIR").map(PathBuf::from);
-
-    let prefix = add_destdir(&prefix, &destdir);
-    let sysconfdir = add_destdir(&sysconfdir, &destdir);
-    let docdir = add_destdir(&docdir, &destdir);
-    let bindir = add_destdir(&bindir, &destdir);
-    let libdir = add_destdir(&libdir, &destdir);
-    let mandir = add_destdir(&mandir, &destdir);
-
-    let empty_dir = build.out.join("tmp/empty_dir");
-    t!(fs::create_dir_all(&empty_dir));
-    if build.config.docs {
-        install_sh(&build, "docs", "rust-docs", &build.rust_package_vers(),
-                   stage, host, &prefix, &sysconfdir, &docdir, &bindir, &libdir,
-                   &mandir, &empty_dir);
-    }
+pub struct Installer<'a> {
+    build: &'a Build,
+    prefix: PathBuf,
+    sysconfdir: PathBuf,
+    docdir: PathBuf,
+    bindir: PathBuf,
+    libdir: PathBuf,
+    mandir: PathBuf,
+}
 
-    for target in build.config.target.iter() {
-        install_sh(&build, "std", "rust-std", &build.rust_package_vers(),
-                   stage, target, &prefix, &sysconfdir, &docdir, &bindir, &libdir,
-                   &mandir, &empty_dir);
-    }
+impl<'a> Installer<'a> {
+    pub fn new(build: &'a Build) -> Installer<'a> {
+        let prefix_default = PathBuf::from("/usr/local");
+        let sysconfdir_default = PathBuf::from("/etc");
+        let docdir_default = PathBuf::from("share/doc/rust");
+        let bindir_default = PathBuf::from("bin");
+        let libdir_default = PathBuf::from("lib");
+        let mandir_default = PathBuf::from("share/man");
+        let prefix = build.config.prefix.as_ref().unwrap_or(&prefix_default);
+        let sysconfdir = build.config.sysconfdir.as_ref().unwrap_or(&sysconfdir_default);
+        let docdir = build.config.docdir.as_ref().unwrap_or(&docdir_default);
+        let bindir = build.config.bindir.as_ref().unwrap_or(&bindir_default);
+        let libdir = build.config.libdir.as_ref().unwrap_or(&libdir_default);
+        let mandir = build.config.mandir.as_ref().unwrap_or(&mandir_default);
+
+        let sysconfdir = prefix.join(sysconfdir);
+        let docdir = prefix.join(docdir);
+        let bindir = prefix.join(bindir);
+        let libdir = prefix.join(libdir);
+        let mandir = prefix.join(mandir);
+
+        let destdir = env::var_os("DESTDIR").map(PathBuf::from);
 
-    if build.config.extended {
-        install_sh(&build, "cargo", "cargo", &build.cargo_package_vers(),
-                   stage, host, &prefix, &sysconfdir, &docdir, &bindir, &libdir,
-                   &mandir, &empty_dir);
-        install_sh(&build, "rls", "rls", &build.rls_package_vers(),
-                   stage, host, &prefix, &sysconfdir, &docdir, &bindir, &libdir,
-                   &mandir, &empty_dir);
+        let prefix = add_destdir(&prefix, &destdir);
+        let sysconfdir = add_destdir(&sysconfdir, &destdir);
+        let docdir = add_destdir(&docdir, &destdir);
+        let bindir = add_destdir(&bindir, &destdir);
+        let libdir = add_destdir(&libdir, &destdir);
+        let mandir = add_destdir(&mandir, &destdir);
+
+        Installer {
+            build,
+            prefix,
+            sysconfdir,
+            docdir,
+            bindir,
+            libdir,
+            mandir,
+        }
     }
 
-    install_sh(&build, "rustc", "rustc", &build.rust_package_vers(),
-               stage, host, &prefix, &sysconfdir, &docdir, &bindir, &libdir,
-               &mandir, &empty_dir);
+    /// Installs everything.
+    pub fn install(&self, stage: u32, host: &str) {
+        let empty_dir = self.build.out.join("tmp/empty_dir");
+        t!(fs::create_dir_all(&empty_dir));
 
-    t!(fs::remove_dir_all(&empty_dir));
-}
+        if self.build.config.docs {
+            self.install_sh("docs", "rust-docs", &self.build.rust_package_vers(),
+                            stage, Some(host), &empty_dir);
+        }
 
-fn install_sh(build: &Build, package: &str, name: &str, version: &str, stage: u32, host: &str,
-              prefix: &Path, sysconfdir: &Path, docdir: &Path, bindir: &Path, libdir: &Path,
-              mandir: &Path, empty_dir: &Path) {
-    println!("Install {} stage{} ({})", package, stage, host);
-    let package_name = format!("{}-{}-{}", name, version, host);
-
-    let mut cmd = Command::new("sh");
-    cmd.current_dir(empty_dir)
-       .arg(sanitize_sh(&tmpdir(build).join(&package_name).join("install.sh")))
-       .arg(format!("--prefix={}", sanitize_sh(prefix)))
-       .arg(format!("--sysconfdir={}", sanitize_sh(sysconfdir)))
-       .arg(format!("--docdir={}", sanitize_sh(docdir)))
-       .arg(format!("--bindir={}", sanitize_sh(bindir)))
-       .arg(format!("--libdir={}", sanitize_sh(libdir)))
-       .arg(format!("--mandir={}", sanitize_sh(mandir)))
-       .arg("--disable-ldconfig");
-    build.run(&mut cmd);
+        for target in self.build.config.target.iter() {
+            self.install_sh("std", "rust-std", &self.build.rust_package_vers(),
+                            stage, Some(target), &empty_dir);
+        }
+
+        if self.build.config.extended {
+            self.install_sh("cargo", "cargo", &self.build.cargo_package_vers(),
+                            stage, Some(host), &empty_dir);
+            self.install_sh("rls", "rls", &self.build.rls_package_vers(),
+                            stage, Some(host), &empty_dir);
+            self.install_sh("analysis", "rust-analysis", &self.build.rust_package_vers(),
+                            stage, Some(host), &empty_dir);
+            self.install_sh("src", "rust-src", &self.build.rust_package_vers(),
+                            stage, None, &empty_dir);
+        }
+
+        self.install_sh("rustc", "rustc", &self.build.rust_package_vers(),
+                        stage, Some(host), &empty_dir);
+
+        t!(fs::remove_dir_all(&empty_dir));
+    }
+
+    fn install_sh(&self, package: &str, name: &str, version: &str,
+                  stage: u32, host: Option<&str>,  empty_dir: &Path) {
+        println!("Install {} stage{} ({:?})", package, stage, host);
+        let package_name = if let Some(host) = host {
+            format!("{}-{}-{}", name, version, host)
+        } else {
+            format!("{}-{}", name, version)
+        };
+
+        let mut cmd = Command::new("sh");
+        cmd.current_dir(empty_dir)
+           .arg(sanitize_sh(&tmpdir(self.build).join(&package_name).join("install.sh")))
+           .arg(format!("--prefix={}", sanitize_sh(&self.prefix)))
+           .arg(format!("--sysconfdir={}", sanitize_sh(&self.sysconfdir)))
+           .arg(format!("--docdir={}", sanitize_sh(&self.docdir)))
+           .arg(format!("--bindir={}", sanitize_sh(&self.bindir)))
+           .arg(format!("--libdir={}", sanitize_sh(&self.libdir)))
+           .arg(format!("--mandir={}", sanitize_sh(&self.mandir)))
+           .arg("--disable-ldconfig");
+        self.build.run(&mut cmd);
+    }
 }
 
 fn add_destdir(path: &Path, destdir: &Option<PathBuf>) -> PathBuf {
diff --git a/src/bootstrap/job.rs b/src/bootstrap/job.rs
index c3859275e6fb4..72a5d1338b8d0 100644
--- a/src/bootstrap/job.rs
+++ b/src/bootstrap/job.rs
@@ -42,6 +42,7 @@
 use std::env;
 use std::io;
 use std::mem;
+use Build;
 
 type HANDLE = *mut u8;
 type BOOL = i32;
@@ -60,8 +61,10 @@ const DUPLICATE_SAME_ACCESS: DWORD = 0x2;
 const PROCESS_DUP_HANDLE: DWORD = 0x40;
 const JobObjectExtendedLimitInformation: JOBOBJECTINFOCLASS = 9;
 const JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE: DWORD = 0x2000;
+const JOB_OBJECT_LIMIT_PRIORITY_CLASS: DWORD = 0x00000020;
 const SEM_FAILCRITICALERRORS: UINT = 0x0001;
 const SEM_NOGPFAULTERRORBOX: UINT = 0x0002;
+const BELOW_NORMAL_PRIORITY_CLASS: DWORD = 0x00004000;
 
 extern "system" {
     fn CreateJobObjectW(lpJobAttributes: *mut u8, lpName: *const u8) -> HANDLE;
@@ -118,7 +121,7 @@ struct JOBOBJECT_BASIC_LIMIT_INFORMATION {
     SchedulingClass: DWORD,
 }
 
-pub unsafe fn setup() {
+pub unsafe fn setup(build: &mut Build) {
     // Tell Windows to not show any UI on errors (such as not finding a required dll
     // during startup or terminating abnormally).  This is important for running tests,
     // since some of them use abnormal termination by design.
@@ -136,6 +139,10 @@ pub unsafe fn setup() {
     // children will reside in the job by default.
     let mut info = mem::zeroed::<JOBOBJECT_EXTENDED_LIMIT_INFORMATION>();
     info.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
+    if build.config.low_priority {
+        info.BasicLimitInformation.LimitFlags |= JOB_OBJECT_LIMIT_PRIORITY_CLASS;
+        info.BasicLimitInformation.PriorityClass = BELOW_NORMAL_PRIORITY_CLASS;
+    }
     let r = SetInformationJobObject(job,
                                     JobObjectExtendedLimitInformation,
                                     &mut info as *mut _ as LPVOID,
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index ca9de43f54219..6ba5196bbbb0f 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -76,6 +76,9 @@ extern crate num_cpus;
 extern crate rustc_serialize;
 extern crate toml;
 
+#[cfg(unix)]
+extern crate libc;
+
 use std::cmp;
 use std::collections::HashMap;
 use std::env;
@@ -108,9 +111,29 @@ pub mod util;
 #[cfg(windows)]
 mod job;
 
-#[cfg(not(windows))]
+#[cfg(unix)]
 mod job {
-    pub unsafe fn setup() {}
+    use libc;
+
+    //apparently glibc defines their own enum for this parameter, in a different type
+    #[cfg(not(any(target_env = "musl", target_env = "musleabi", target_env = "musleabihf",
+                  target_os = "emscripten", target_arch = "mips", target_arch = "mipsel")))]
+    const PRIO_PGRP: libc::c_uint = libc::PRIO_PGRP as libc::c_uint;
+    #[cfg(any(target_env = "musl", target_env = "musleabi", target_env = "musleabihf",
+              target_os = "emscripten", target_arch = "mips", target_arch = "mipsel"))]
+    const PRIO_PGRP: libc::c_int = libc::PRIO_PGRP;
+
+    pub unsafe fn setup(build: &mut ::Build) {
+        if build.config.low_priority {
+            libc::setpriority(PRIO_PGRP, 0, 10);
+        }
+    }
+}
+
+#[cfg(not(any(unix, windows)))]
+mod job {
+    pub unsafe fn setup(_build: &mut ::Build) {
+    }
 }
 
 pub use config::Config;
@@ -263,7 +286,7 @@ impl Build {
     /// Executes the entire build, as configured by the flags and configuration.
     pub fn build(&mut self) {
         unsafe {
-            job::setup();
+            job::setup(self);
         }
 
         if let Subcommand::Clean = self.flags.cmd {
diff --git a/src/bootstrap/step.rs b/src/bootstrap/step.rs
index 92666e8e63907..57915446e1d1a 100644
--- a/src/bootstrap/step.rs
+++ b/src/bootstrap/step.rs
@@ -761,7 +761,7 @@ pub fn build_rules<'a>(build: &'a Build) -> Rules {
          .run(move |s| dist::rls(build, s.stage, s.target));
     rules.dist("install", "path/to/nowhere")
          .dep(|s| s.name("default:dist"))
-         .run(move |s| install::install(build, s.stage, s.target));
+         .run(move |s| install::Installer::new(build).install(s.stage, s.target));
     rules.dist("dist-cargo", "cargo")
          .host(true)
          .only_host_build(true)
diff --git a/src/librustc/hir/map/definitions.rs b/src/librustc/hir/map/definitions.rs
index 6118df2ddfc89..9537b40b28a0b 100644
--- a/src/librustc/hir/map/definitions.rs
+++ b/src/librustc/hir/map/definitions.rs
@@ -16,6 +16,7 @@
 
 use hir;
 use hir::def_id::{CrateNum, DefId, DefIndex, LOCAL_CRATE, DefIndexAddressSpace};
+use ich::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_data_structures::stable_hasher::StableHasher;
@@ -34,7 +35,7 @@ use util::nodemap::NodeMap;
 pub struct DefPathTable {
     index_to_key: [Vec<DefKey>; 2],
     key_to_index: FxHashMap<DefKey, DefIndex>,
-    def_path_hashes: [Vec<u64>; 2],
+    def_path_hashes: [Vec<Fingerprint>; 2],
 }
 
 // Unfortunately we have to provide a manual impl of Clone because of the
@@ -55,7 +56,7 @@ impl DefPathTable {
 
     fn allocate(&mut self,
                 key: DefKey,
-                def_path_hash: u64,
+                def_path_hash: Fingerprint,
                 address_space: DefIndexAddressSpace)
                 -> DefIndex {
         let index = {
@@ -79,7 +80,7 @@ impl DefPathTable {
     }
 
     #[inline(always)]
-    pub fn def_path_hash(&self, index: DefIndex) -> u64 {
+    pub fn def_path_hash(&self, index: DefIndex) -> Fingerprint {
         self.def_path_hashes[index.address_space().index()]
                             [index.as_array_index()]
     }
@@ -146,8 +147,8 @@ impl Decodable for DefPathTable {
         let index_to_key_lo: Vec<DefKey> = Decodable::decode(d)?;
         let index_to_key_hi: Vec<DefKey> = Decodable::decode(d)?;
 
-        let def_path_hashes_lo: Vec<u64> = Decodable::decode(d)?;
-        let def_path_hashes_hi: Vec<u64> = Decodable::decode(d)?;
+        let def_path_hashes_lo: Vec<Fingerprint> = Decodable::decode(d)?;
+        let def_path_hashes_hi: Vec<Fingerprint> = Decodable::decode(d)?;
 
         let index_to_key = [index_to_key_lo, index_to_key_hi];
         let def_path_hashes = [def_path_hashes_lo, def_path_hashes_hi];
@@ -210,7 +211,7 @@ pub struct DefKey {
 }
 
 impl DefKey {
-    fn compute_stable_hash(&self, parent_hash: u64) -> u64 {
+    fn compute_stable_hash(&self, parent_hash: Fingerprint) -> Fingerprint {
         let mut hasher = StableHasher::new();
 
         // We hash a 0u8 here to disambiguate between regular DefPath hashes,
@@ -221,7 +222,7 @@ impl DefKey {
         hasher.finish()
     }
 
-    fn root_parent_stable_hash(crate_name: &str, crate_disambiguator: &str) -> u64 {
+    fn root_parent_stable_hash(crate_name: &str, crate_disambiguator: &str) -> Fingerprint {
         let mut hasher = StableHasher::new();
         // Disambiguate this from a regular DefPath hash,
         // see compute_stable_hash() above.
@@ -396,7 +397,7 @@ impl Definitions {
     }
 
     #[inline(always)]
-    pub fn def_path_hash(&self, index: DefIndex) -> u64 {
+    pub fn def_path_hash(&self, index: DefIndex) -> Fingerprint {
         self.table.def_path_hash(index)
     }
 
diff --git a/src/librustc/ich/fingerprint.rs b/src/librustc/ich/fingerprint.rs
index ccdbab88b8b9c..a947f6aeff709 100644
--- a/src/librustc/ich/fingerprint.rs
+++ b/src/librustc/ich/fingerprint.rs
@@ -10,95 +10,75 @@
 
 use rustc_serialize::{Encodable, Decodable, Encoder, Decoder};
 use rustc_data_structures::stable_hasher;
-use rustc_data_structures::ToHex;
-
-const FINGERPRINT_LENGTH: usize = 16;
+use std::mem;
+use std::slice;
 
 #[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Clone, Copy)]
-pub struct Fingerprint(pub [u8; FINGERPRINT_LENGTH]);
+pub struct Fingerprint(u64, u64);
 
 impl Fingerprint {
     #[inline]
     pub fn zero() -> Fingerprint {
-        Fingerprint([0; FINGERPRINT_LENGTH])
+        Fingerprint(0, 0)
     }
 
+    #[inline]
     pub fn from_smaller_hash(hash: u64) -> Fingerprint {
-        let mut result = Fingerprint::zero();
-        result.0[0] = (hash >>  0) as u8;
-        result.0[1] = (hash >>  8) as u8;
-        result.0[2] = (hash >> 16) as u8;
-        result.0[3] = (hash >> 24) as u8;
-        result.0[4] = (hash >> 32) as u8;
-        result.0[5] = (hash >> 40) as u8;
-        result.0[6] = (hash >> 48) as u8;
-        result.0[7] = (hash >> 56) as u8;
-        result
+        Fingerprint(hash, hash)
     }
 
+    #[inline]
     pub fn to_smaller_hash(&self) -> u64 {
-        ((self.0[0] as u64) <<  0) |
-        ((self.0[1] as u64) <<  8) |
-        ((self.0[2] as u64) << 16) |
-        ((self.0[3] as u64) << 24) |
-        ((self.0[4] as u64) << 32) |
-        ((self.0[5] as u64) << 40) |
-        ((self.0[6] as u64) << 48) |
-        ((self.0[7] as u64) << 56)
+        self.0
     }
 
     pub fn to_hex(&self) -> String {
-        self.0.to_hex()
+        format!("{:x}{:x}", self.0, self.1)
     }
 }
 
 impl Encodable for Fingerprint {
     #[inline]
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
-        for &byte in &self.0 {
-            s.emit_u8(byte)?;
-        }
-        Ok(())
+        s.emit_u64(self.0.to_le())?;
+        s.emit_u64(self.1.to_le())
     }
 }
 
 impl Decodable for Fingerprint {
     #[inline]
     fn decode<D: Decoder>(d: &mut D) -> Result<Fingerprint, D::Error> {
-        let mut result = Fingerprint([0u8; FINGERPRINT_LENGTH]);
-        for byte in &mut result.0 {
-            *byte = d.read_u8()?;
-        }
-        Ok(result)
+        let _0 = u64::from_le(d.read_u64()?);
+        let _1 = u64::from_le(d.read_u64()?);
+        Ok(Fingerprint(_0, _1))
     }
 }
 
 impl ::std::fmt::Display for Fingerprint {
     fn fmt(&self, formatter: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
-        for i in 0 .. self.0.len() {
-            if i > 0 {
-                write!(formatter, "::")?;
-            }
-
-            write!(formatter, "{}", self.0[i])?;
-        }
-        Ok(())
+        write!(formatter, "{:x}-{:x}", self.0, self.1)
     }
 }
 
-
 impl stable_hasher::StableHasherResult for Fingerprint {
     fn finish(mut hasher: stable_hasher::StableHasher<Self>) -> Self {
-        let mut fingerprint = Fingerprint::zero();
-        fingerprint.0.copy_from_slice(hasher.finalize());
-        fingerprint
+        let hash_bytes: &[u8] = hasher.finalize();
+
+        assert!(hash_bytes.len() >= mem::size_of::<u64>() * 2);
+        let hash_bytes: &[u64] = unsafe {
+            slice::from_raw_parts(hash_bytes.as_ptr() as *const u64, 2)
+        };
+
+        // The bytes returned bytes the Blake2B hasher are always little-endian.
+        Fingerprint(u64::from_le(hash_bytes[0]), u64::from_le(hash_bytes[1]))
     }
 }
 
 impl<CTX> stable_hasher::HashStable<CTX> for Fingerprint {
+    #[inline]
     fn hash_stable<W: stable_hasher::StableHasherResult>(&self,
                                           _: &mut CTX,
                                           hasher: &mut stable_hasher::StableHasher<W>) {
-        ::std::hash::Hash::hash(&self.0, hasher);
+        ::std::hash::Hash::hash(self, hasher);
     }
 }
diff --git a/src/librustc/ich/hcx.rs b/src/librustc/ich/hcx.rs
index 786d1c5035d96..f25ec8ecd4d71 100644
--- a/src/librustc/ich/hcx.rs
+++ b/src/librustc/ich/hcx.rs
@@ -110,7 +110,7 @@ impl<'a, 'tcx: 'a> StableHashingContext<'a, 'tcx> {
     }
 
     #[inline]
-    pub fn def_path_hash(&mut self, def_id: DefId) -> u64 {
+    pub fn def_path_hash(&mut self, def_id: DefId) -> ich::Fingerprint {
         self.tcx.def_path_hash(def_id)
     }
 
diff --git a/src/librustc/middle/cstore.rs b/src/librustc/middle/cstore.rs
index a68aca4600054..8ad1db7859566 100644
--- a/src/librustc/middle/cstore.rs
+++ b/src/librustc/middle/cstore.rs
@@ -282,7 +282,7 @@ pub trait CrateStore {
                     -> Option<DefId>;
     fn def_key(&self, def: DefId) -> DefKey;
     fn def_path(&self, def: DefId) -> hir_map::DefPath;
-    fn def_path_hash(&self, def: DefId) -> u64;
+    fn def_path_hash(&self, def: DefId) -> ich::Fingerprint;
     fn struct_field_names(&self, def: DefId) -> Vec<ast::Name>;
     fn item_children(&self, did: DefId) -> Vec<def::Export>;
     fn load_macro(&self, did: DefId, sess: &Session) -> LoadedMacro;
@@ -414,7 +414,7 @@ impl CrateStore for DummyCrateStore {
     fn def_path(&self, def: DefId) -> hir_map::DefPath {
         bug!("relative_def_path")
     }
-    fn def_path_hash(&self, def: DefId) -> u64 {
+    fn def_path_hash(&self, def: DefId) -> ich::Fingerprint {
         bug!("wa")
     }
     fn struct_field_names(&self, def: DefId) -> Vec<ast::Name> { bug!("struct_field_names") }
diff --git a/src/librustc/session/filesearch.rs b/src/librustc/session/filesearch.rs
index 82c2425aead73..47b988a21b4c1 100644
--- a/src/librustc/session/filesearch.rs
+++ b/src/librustc/session/filesearch.rs
@@ -159,9 +159,14 @@ pub fn get_or_default_sysroot() -> PathBuf {
         })
     }
 
-    match canonicalize(env::current_exe().ok()) {
-        Some(mut p) => { p.pop(); p.pop(); p }
-        None => bug!("can't determine value for sysroot")
+    match env::current_exe() {
+        Ok(exe) => {
+            match canonicalize(Some(exe)) {
+                Some(mut p) => { p.pop(); p.pop(); return p; },
+                None => bug!("can't determine value for sysroot")
+            }
+        }
+        Err(ref e) => panic!(format!("failed to get current_exe: {}", e))
     }
 }
 
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index a86d7351ef472..359722ce96ec9 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -19,7 +19,7 @@ use dep_graph::DepNode;
 use hir::{map as hir_map, FreevarMap, TraitMap};
 use hir::def::{Def, CtorKind, ExportMap};
 use hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
-use ich::StableHashingContext;
+use ich::{self, StableHashingContext};
 use middle::const_val::ConstVal;
 use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
 use middle::privacy::AccessLevels;
@@ -2248,7 +2248,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     #[inline]
-    pub fn def_path_hash(self, def_id: DefId) -> u64 {
+    pub fn def_path_hash(self, def_id: DefId) -> ich::Fingerprint {
         if def_id.is_local() {
             self.hir.definitions().def_path_hash(def_id.index)
         } else {
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index cfbf1244db3ad..348d164af4190 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -29,6 +29,7 @@ use util::nodemap::FxHashMap;
 use serialize;
 
 use hir;
+use ich;
 
 use self::InferTy::*;
 use self::TypeVariants::*;
@@ -849,7 +850,7 @@ impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
         self.item_name // safe to skip the binder to access a name
     }
 
-    pub fn sort_key(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> (u64, InternedString) {
+    pub fn sort_key(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> (ich::Fingerprint, InternedString) {
         // We want something here that is stable across crate boundaries.
         // The DefId isn't but the `deterministic_hash` of the corresponding
         // DefPath is.
@@ -884,7 +885,7 @@ impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
         self.skip_binder().item_name()
     }
 
-    pub fn sort_key(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> (u64, InternedString) {
+    pub fn sort_key(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> (ich::Fingerprint, InternedString) {
         self.skip_binder().sort_key(tcx)
     }
 
diff --git a/src/librustc/ty/trait_def.rs b/src/librustc/ty/trait_def.rs
index 865297c7ecbfd..86774136bd6cb 100644
--- a/src/librustc/ty/trait_def.rs
+++ b/src/librustc/ty/trait_def.rs
@@ -9,6 +9,7 @@
 // except according to those terms.
 
 use hir::def_id::DefId;
+use ich::Fingerprint;
 use traits::specialization_graph;
 use ty::fast_reject;
 use ty::fold::TypeFoldable;
@@ -32,7 +33,7 @@ pub struct TraitDef {
 
     /// The ICH of this trait's DefPath, cached here so it doesn't have to be
     /// recomputed all the time.
-    pub def_path_hash: u64,
+    pub def_path_hash: Fingerprint,
 }
 
 // We don't store the list of impls in a flat list because each cached list of
@@ -94,7 +95,7 @@ impl<'a, 'gcx, 'tcx> TraitDef {
                unsafety: hir::Unsafety,
                paren_sugar: bool,
                has_default_impl: bool,
-               def_path_hash: u64)
+               def_path_hash: Fingerprint)
                -> TraitDef {
         TraitDef {
             def_id,
diff --git a/src/librustc_incremental/calculate_svh/mod.rs b/src/librustc_incremental/calculate_svh/mod.rs
index 8cdabc1d894e2..c9ed9ad3c7d2d 100644
--- a/src/librustc_incremental/calculate_svh/mod.rs
+++ b/src/librustc_incremental/calculate_svh/mod.rs
@@ -224,7 +224,7 @@ impl<'a, 'tcx: 'a> ComputeItemHashesVisitor<'a, 'tcx> {
     {
         let tcx = self.hcx.tcx();
 
-        let mut impls: Vec<(u64, Fingerprint)> = krate
+        let mut impls: Vec<(Fingerprint, Fingerprint)> = krate
             .trait_impls
             .iter()
             .map(|(&trait_id, impls)| {
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index 4b7083590d24a..7478f902e061a 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -17,6 +17,7 @@ use rustc::middle::cstore::{CrateStore, CrateSource, LibSource, DepKind,
                             ExternCrate, NativeLibrary, MetadataLoader, LinkMeta,
                             LinkagePreference, LoadedMacro, EncodedMetadata};
 use rustc::hir::def;
+use rustc::ich;
 use rustc::middle::lang_items;
 use rustc::session::Session;
 use rustc::ty::{self, TyCtxt};
@@ -337,7 +338,7 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(def.krate).def_path(def.index)
     }
 
-    fn def_path_hash(&self, def: DefId) -> u64 {
+    fn def_path_hash(&self, def: DefId) -> ich::Fingerprint {
         self.get_crate_data(def.krate).def_path_hash(def.index)
     }
 
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index 754f27810c453..d8826d87d4d0f 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -16,6 +16,7 @@ use schema::*;
 use rustc::dep_graph::{DepGraph, DepNode, GlobalMetaDataKind};
 use rustc::hir::map::{DefKey, DefPath, DefPathData};
 use rustc::hir;
+use rustc::ich;
 
 use rustc::middle::cstore::LinkagePreference;
 use rustc::hir::def::{self, Def, CtorKind};
@@ -1106,7 +1107,7 @@ impl<'a, 'tcx> CrateMetadata {
     }
 
     #[inline]
-    pub fn def_path_hash(&self, index: DefIndex) -> u64 {
+    pub fn def_path_hash(&self, index: DefIndex) -> ich::Fingerprint {
         self.def_path_table.def_path_hash(index)
     }
 
diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index c115a6ccba609..f09ce1cc64849 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -215,14 +215,14 @@
         } else if (ev.target.tagName === 'SPAN' && hasClass(ev.target.parentNode, 'line-numbers')) {
             var prev_id = 0;
 
-            function set_fragment(name) {
+            var set_fragment = function (name) {
                 if (browserSupportsHistoryApi()) {
                     history.replaceState(null, null, '#' + name);
                     window.hashchange();
                 } else {
                     location.replace('#' + name);
                 }
-            }
+            };
 
             var cur_id = parseInt(ev.target.id, 10);
 
@@ -685,7 +685,7 @@
         }
 
         function escape(content) {
-            let h1 = document.createElement('h1');
+            var h1 = document.createElement('h1');
             h1.textContent = content;
             return h1.innerHTML;
         }
diff --git a/src/libstd/env.rs b/src/libstd/env.rs
index 64eb52e28bc42..96c10c5d10d1a 100644
--- a/src/libstd/env.rs
+++ b/src/libstd/env.rs
@@ -43,16 +43,19 @@ use sys::os as os_imp;
 /// use std::env;
 ///
 /// // We assume that we are in a valid directory.
-/// let p = env::current_dir().unwrap();
-/// println!("The current directory is {}", p.display());
+/// let path = env::current_dir().unwrap();
+/// println!("The current directory is {}", path.display());
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn current_dir() -> io::Result<PathBuf> {
     os_imp::getcwd()
 }
 
-/// Changes the current working directory to the specified path, returning
-/// whether the change was completed successfully or not.
+/// Changes the current working directory to the specified path.
+///
+/// Returns an [`Err`] if the operation fails.
+///
+/// [`Err`]: ../../std/result/enum.Result.html#method.err
 ///
 /// # Examples
 ///
@@ -65,8 +68,8 @@ pub fn current_dir() -> io::Result<PathBuf> {
 /// println!("Successfully changed working directory to {}!", root.display());
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
-pub fn set_current_dir<P: AsRef<Path>>(p: P) -> io::Result<()> {
-    os_imp::chdir(p.as_ref())
+pub fn set_current_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
+    os_imp::chdir(path.as_ref())
 }
 
 /// An iterator over a snapshot of the environment variables of this process.
@@ -175,10 +178,10 @@ impl fmt::Debug for VarsOs {
 ///
 /// The returned result is [`Ok(s)`] if the environment variable is present and is
 /// valid unicode. If the environment variable is not present, or it is not
-/// valid unicode, then [`Err`] will be returned.
+/// valid unicode, then [`VarError`] will be returned.
 ///
 /// [`Ok(s)`]: ../result/enum.Result.html#variant.Ok
-/// [`Err`]: ../result/enum.Result.html#variant.Err
+/// [`VarError`]: enum.VarError.html
 ///
 /// # Examples
 ///
@@ -199,7 +202,7 @@ pub fn var<K: AsRef<OsStr>>(key: K) -> Result<String, VarError> {
 fn _var(key: &OsStr) -> Result<String, VarError> {
     match var_os(key) {
         Some(s) => s.into_string().map_err(VarError::NotUnicode),
-        None => Err(VarError::NotPresent)
+        None => Err(VarError::NotPresent),
     }
 }
 
diff --git a/src/libstd/process.rs b/src/libstd/process.rs
index 3896fc20a2dde..d0e7defbbbb9a 100644
--- a/src/libstd/process.rs
+++ b/src/libstd/process.rs
@@ -754,6 +754,13 @@ impl fmt::Debug for Stdio {
 }
 
 /// Describes the result of a process after it has terminated.
+///
+/// This `struct` is used to represent the exit status of a child process.
+/// Child processes are created via the [`Command`] struct and their exit
+/// status is exposed through the [`status`] method.
+///
+/// [`Command`]: struct.Command.html
+/// [`status`]: struct.Command.html#method.status
 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
 #[stable(feature = "process", since = "1.0.0")]
 pub struct ExitStatus(imp::ExitStatus);
@@ -788,6 +795,22 @@ impl ExitStatus {
     /// On Unix, this will return `None` if the process was terminated
     /// by a signal; `std::os::unix` provides an extension trait for
     /// extracting the signal and other details from the `ExitStatus`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::process::Command;
+    ///
+    /// let status = Command::new("mkdir")
+    ///                      .arg("projects")
+    ///                      .status()
+    ///                      .expect("failed to execute mkdir");
+    ///
+    /// match status.code() {
+    ///     Some(code) => println!("Exited with status code: {}", code),
+    ///     None       => println!("Process terminated by signal")
+    /// }
+    /// ```
     #[stable(feature = "process", since = "1.0.0")]
     pub fn code(&self) -> Option<i32> {
         self.0.code()
diff --git a/src/libstd/sync/mpsc/mod.rs b/src/libstd/sync/mpsc/mod.rs
index 2cb649ce67b9c..284a5fbd9d506 100644
--- a/src/libstd/sync/mpsc/mod.rs
+++ b/src/libstd/sync/mpsc/mod.rs
@@ -1067,7 +1067,7 @@ impl<T> Receiver<T> {
         Receiver { inner: UnsafeCell::new(inner) }
     }
 
-    /// Attempts to return a pending value on this receiver without blocking
+    /// Attempts to return a pending value on this receiver without blocking.
     ///
     /// This method will never block the caller in order to wait for data to
     /// become available. Instead, this will always return immediately with a
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 36928696c4059..8e41fd009be67 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -253,7 +253,12 @@ pub fn current_exe() -> io::Result<PathBuf> {
 
 #[cfg(any(target_os = "linux", target_os = "android", target_os = "emscripten"))]
 pub fn current_exe() -> io::Result<PathBuf> {
-    ::fs::read_link("/proc/self/exe")
+    let selfexe = PathBuf::from("/proc/self/exe");
+    if selfexe.exists() {
+        ::fs::read_link(selfexe)
+    } else {
+        Err(io::Error::new(io::ErrorKind::Other, "no /proc/self/exe available. Is /proc mounted?"))
+    }
 }
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
diff --git a/src/tools/cargo b/src/tools/cargo
index 41e490480b01e..397359840ecad 160000
--- a/src/tools/cargo
+++ b/src/tools/cargo
@@ -1 +1 @@
-Subproject commit 41e490480b01ef8d15ef061b578fbf1e08d0faa9
+Subproject commit 397359840ecad02d5fe69b2a0cf328e98235ffea