5 files changed, 25 insertions, 3 deletions
diff --git a/src/librustc_codegen_llvm/attributes.rs b/src/librustc_codegen_llvm/attributes.rs
index 2b64642b766..c8a2b47e98d 100644
--- a/src/librustc_codegen_llvm/attributes.rs
+++ b/src/librustc_codegen_llvm/attributes.rs
@@ -124,7 +124,8 @@ pub fn llvm_target_features(sess: &Session) -> impl Iterator<Item = &str> {
 }
 
 pub fn apply_target_cpu_attr(cx: &CodegenCx<'ll, '_>, llfn: &'ll Value) {
-    let target_cpu = CString::new(cx.tcx.sess.target_cpu().to_string()).unwrap();
+    let cpu = llvm_util::target_cpu(cx.tcx.sess);
+    let target_cpu = CString::new(cpu).unwrap();
     llvm::AddFunctionAttrStringValue(
             llfn,
             llvm::AttributePlace::Function,
diff --git a/src/librustc_codegen_llvm/back/linker.rs b/src/librustc_codegen_llvm/back/linker.rs
index a429e8f2d81..eee60b262a1 100644
--- a/src/librustc_codegen_llvm/back/linker.rs
+++ b/src/librustc_codegen_llvm/back/linker.rs
@@ -26,6 +26,7 @@ use rustc::session::config::{self, CrateType, OptLevel, DebugInfo,
 use rustc::ty::TyCtxt;
 use rustc_target::spec::{LinkerFlavor, LldFlavor};
 use serialize::{json, Encoder};
+use llvm_util;
 
 /// For all the linkers we support, and information they might
 /// need out of the shared crate context before we get rid of it.
@@ -202,7 +203,7 @@ impl<'a> GccLinker<'a> {
         };
 
         self.linker_arg(&format!("-plugin-opt={}", opt_level));
-        self.linker_arg(&format!("-plugin-opt=mcpu={}", self.sess.target_cpu()));
+        self.linker_arg(&format!("-plugin-opt=mcpu={}", llvm_util::target_cpu(self.sess)));
 
         match self.sess.opts.cg.lto {
             config::Lto::Thin |
diff --git a/src/librustc_codegen_llvm/back/write.rs b/src/librustc_codegen_llvm/back/write.rs
index 80e9965e39c..2373428d68c 100644
--- a/src/librustc_codegen_llvm/back/write.rs
+++ b/src/librustc_codegen_llvm/back/write.rs
@@ -25,6 +25,7 @@ use rustc::session::Session;
 use rustc::util::nodemap::FxHashMap;
 use time_graph::{self, TimeGraph, Timeline};
 use llvm::{self, DiagnosticInfo, PassManager, SMDiagnostic};
+use llvm_util;
 use {CodegenResults, ModuleSource, ModuleCodegen, CompiledModule, ModuleKind};
 use CrateInfo;
 use rustc::hir::def_id::{CrateNum, LOCAL_CRATE};
@@ -173,7 +174,7 @@ pub fn target_machine_factory(sess: &Session, find_features: bool)
     let singlethread = sess.target.target.options.singlethread;
 
     let triple = SmallCStr::new(&sess.target.target.llvm_target);
-    let cpu = SmallCStr::new(sess.target_cpu());
+    let cpu = SmallCStr::new(llvm_util::target_cpu(sess));
     let features = attributes::llvm_target_features(sess)
         .collect::<Vec<_>>()
         .join(",");
diff --git a/src/librustc_codegen_llvm/llvm/ffi.rs b/src/librustc_codegen_llvm/llvm/ffi.rs
index d3039a05b6d..51b0299e63f 100644
--- a/src/librustc_codegen_llvm/llvm/ffi.rs
+++ b/src/librustc_codegen_llvm/llvm/ffi.rs
@@ -1449,6 +1449,7 @@ extern "C" {
     pub fn LLVMRustPrintTargetCPUs(T: &TargetMachine);
     pub fn LLVMRustPrintTargetFeatures(T: &TargetMachine);
 
+    pub fn LLVMRustGetHostCPUName(len: *mut usize) -> *const c_char;
     pub fn LLVMRustCreateTargetMachine(Triple: *const c_char,
                                        CPU: *const c_char,
                                        Features: *const c_char,
diff --git a/src/librustc_codegen_llvm/llvm_util.rs b/src/librustc_codegen_llvm/llvm_util.rs
index ff26e0f35f0..9fcc33d82cf 100644
--- a/src/librustc_codegen_llvm/llvm_util.rs
+++ b/src/librustc_codegen_llvm/llvm_util.rs
@@ -17,6 +17,8 @@ use libc::c_int;
 use std::ffi::CString;
 use syntax::feature_gate::UnstableFeatures;
 
+use std::str;
+use std::slice;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Once;
 
@@ -262,3 +264,19 @@ pub(crate) fn print(req: PrintRequest, sess: &Session) {
         }
     }
 }
+
+pub fn target_cpu(sess: &Session) -> &str {
+    let name = match sess.opts.cg.target_cpu {
+        Some(ref s) => &**s,
+        None => &*sess.target.target.options.cpu
+    };
+    if name != "native" {
+        return name
+    }
+
+    unsafe {
+        let mut len = 0;
+        let ptr = llvm::LLVMRustGetHostCPUName(&mut len);
+        str::from_utf8(slice::from_raw_parts(ptr as *const u8, len)).unwrap()
+    }
+}