Index: clang/lib/Basic/Targets.cpp
===================================================================
--- clang/lib/Basic/Targets.cpp
+++ clang/lib/Basic/Targets.cpp
@@ -471,6 +471,7 @@
     case llvm::Triple::ppc:
     case llvm::Triple::ppc64:
     case llvm::Triple::ppc64le:
+    case llvm::Triple::aarch64:
       this->MCountName = "_mcount";
       break;
     case llvm::Triple::x86:
Index: clang/test/Frontend/gnu-mcount.c
===================================================================
--- clang/test/Frontend/gnu-mcount.c
+++ clang/test/Frontend/gnu-mcount.c
@@ -6,6 +6,7 @@
 // RUN: %clang -target armv7-unknown-linux-gnueabi -meabi gnu -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM-EABI-MEABI-GNU
 // RUN: %clang -target aarch64-unknown-linux-gnueabi -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM64-EABI
 // RUN: %clang -target aarch64-unknown-linux-gnueabi -meabi gnu -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM64-EABI-MEABI-GNU
+// RUN: %clang -target aarch64-unknown-linux-gnu -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM64-LINUX-GNU
 // RUN: %clang -target armv7-unknown-linux-gnueabihf -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM-EABI
 // RUN: %clang -target armv7-unknown-linux-gnueabihf -meabi gnu -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM-EABI-MEABI-GNU
 // RUN: %clang -target aarch64-unknown-linux-gnueabihf -pg -S -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK -check-prefix CHECK-ARM64-EABI
@@ -44,6 +45,7 @@
 }
 
 // CHECK-LABEL: f
+// CHECK-ARM64-LINUX-GNU: call void @_mcount()
 // CHECK-ARM-IOS-NOT: call void @_mcount()
 // CHECK-ARM-IOS-NOT: call void @"\01__gnu_mcount_nc"()
 // CHECK-ARM-EABI: call void @"\01mcount"()