Index: lib/Target/ARM64/ARM64Subtarget.cpp
===================================================================
--- lib/Target/ARM64/ARM64Subtarget.cpp
+++ lib/Target/ARM64/ARM64Subtarget.cpp
@@ -90,8 +90,11 @@
 /// memset with zero passed as the second argument. Otherwise it
 /// returns null.
 const char *ARM64Subtarget::getBZeroEntry() const {
-  // At the moment, always prefer bzero.
-  return "bzero";
+  // Prefer bzero on Darwin only.
+  if(isTargetDarwin())
+    return "bzero";
+
+  return nullptr;
 }
 
 void ARM64Subtarget::overrideSchedPolicy(MachineSchedPolicy &Policy,
Index: test/CodeGen/ARM64/memset-to-bzero.ll
===================================================================
--- test/CodeGen/ARM64/memset-to-bzero.ll
+++ test/CodeGen/ARM64/memset-to-bzero.ll
@@ -1,4 +1,7 @@
-; RUN: llc %s -march arm64 -o - | FileCheck %s
+; RUN: llc %s -mtriple=arm64-apple-darwin -o - | \
+; RUN:   FileCheck --check-prefix=CHECK-DARWIN --check-prefix=CHECK %s
+; RUN: llc %s -mtriple=arm64-linux-gnu -o - | \
+; RUN:   FileCheck --check-prefix=CHECK-LINUX --check-prefix=CHECK %s
 ; <rdar://problem/14199482> ARM64: Calls to bzero() replaced with calls to memset()
 
 ; CHECK: @fct1
@@ -14,7 +17,8 @@
 
 ; CHECK: @fct2
 ; When the size is bigger than 256, change into bzero.
-; CHECK: bzero
+; CHECK-DARWIN: bzero
+; CHECK-LINUX: memset
 define void @fct2(i8* nocapture %ptr) {
 entry:
   tail call void @llvm.memset.p0i8.i64(i8* %ptr, i8 0, i64 257, i32 1, i1 false)
@@ -23,7 +27,8 @@
 
 ; CHECK: @fct3
 ; For unknown size, change to bzero.
-; CHECK: bzero
+; CHECK-DARWIN: bzero
+; CHECK-LINUX: memset
 define void @fct3(i8* nocapture %ptr, i32 %unknown) {
 entry:
   %conv = sext i32 %unknown to i64
@@ -47,7 +52,8 @@
 
 ; CHECK: @fct5
 ; Size > 256, change.
-; CHECK: bzero
+; CHECK-DARWIN: bzero
+; CHECK-LINUX: memset
 define void @fct5(i8* %ptr) {
 entry:
   %tmp = tail call i64 @llvm.objectsize.i64(i8* %ptr, i1 false)
@@ -57,7 +63,8 @@
 
 ; CHECK: @fct6
 ; Size = unknown, change.
-; CHECK: bzero
+; CHECK-DARWIN: bzero
+; CHECK-LINUX: memset
 define void @fct6(i8* %ptr, i32 %unknown) {
 entry:
   %conv = sext i32 %unknown to i64