diff --git a/src/librustc_back/target/apple_ios_base.rs b/src/librustc_back/target/apple_ios_base.rs
index f9dcb4fb812..ac133cabc3b 100644
--- a/src/librustc_back/target/apple_ios_base.rs
+++ b/src/librustc_back/target/apple_ios_base.rs
@@ -14,6 +14,7 @@
 use self::Arch::*;
 
 #[allow(non_camel_case_types)]
+#[derive(Copy)]
 pub enum Arch {
     Armv7,
     Armv7s,
@@ -70,8 +71,16 @@ fn pre_link_args(arch: Arch) -> Vec<String> {
          "-Wl,-syslibroot".to_string(), get_sdk_root(sdk_name)]
 }
 
+fn target_cpu(arch: Arch) -> String {
+    match arch {
+        X86_64 => "x86-64",
+        _ => "generic",
+    }.to_string()
+}
+
 pub fn opts(arch: Arch) -> TargetOptions {
     TargetOptions {
+        cpu: target_cpu(arch),
         dynamic_linking: false,
         executables: true,
         // Although there is an experimental implementation of LLVM which
diff --git a/src/librustc_back/target/x86_64_apple_darwin.rs b/src/librustc_back/target/x86_64_apple_darwin.rs
index 0ebd3bd3215..f2abfd4564c 100644
--- a/src/librustc_back/target/x86_64_apple_darwin.rs
+++ b/src/librustc_back/target/x86_64_apple_darwin.rs
@@ -12,6 +12,7 @@
 
 pub fn target() -> Target {
     let mut base = super::apple_base::opts();
+    base.cpu = "x86-64".to_string();
     base.eliminate_frame_pointer = false;
     base.pre_link_args.push("-m64".to_string());
 
diff --git a/src/librustc_back/target/x86_64_pc_windows_gnu.rs b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
index 9e1294a8962..6b3054656fe 100644
--- a/src/librustc_back/target/x86_64_pc_windows_gnu.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
@@ -12,6 +12,7 @@
 
 pub fn target() -> Target {
     let mut base = super::windows_base::opts();
+    base.cpu = "x86-64".to_string();
     // On Win64 unwinding is handled by the OS, so we can link libgcc statically.
     base.pre_link_args.push("-static-libgcc".to_string());
     base.pre_link_args.push("-m64".to_string());
diff --git a/src/librustc_back/target/x86_64_unknown_dragonfly.rs b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
index 6635306b0e1..676aaecc2fc 100644
--- a/src/librustc_back/target/x86_64_unknown_dragonfly.rs
+++ b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
@@ -12,6 +12,7 @@
 
 pub fn target() -> Target {
     let mut base = super::dragonfly_base::opts();
+    base.cpu = "x86-64".to_string();
     base.pre_link_args.push("-m64".to_string());
 
     Target {
diff --git a/src/librustc_back/target/x86_64_unknown_freebsd.rs b/src/librustc_back/target/x86_64_unknown_freebsd.rs
index 2aba2b8defb..3275cb07b5a 100644
--- a/src/librustc_back/target/x86_64_unknown_freebsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_freebsd.rs
@@ -12,6 +12,7 @@
 
 pub fn target() -> Target {
     let mut base = super::freebsd_base::opts();
+    base.cpu = "x86-64".to_string();
     base.pre_link_args.push("-m64".to_string());
 
     Target {
diff --git a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
index d7a6df3a8b0..49c4ad4aea9 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
@@ -12,6 +12,7 @@
 
 pub fn target() -> Target {
     let mut base = super::linux_base::opts();
+    base.cpu = "x86-64".to_string();
     base.pre_link_args.push("-m64".to_string());
 
     Target {