Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -87,7 +87,7 @@
     cl::Hidden);
 
 static cl::opt<bool> ExperimentalUnorderedISEL(
-    "x86-experimental-unordered-atomic-isel", cl::init(false),
+    "x86-experimental-unordered-atomic-isel", cl::init(true),
     cl::desc("Use LoadSDNode and StoreSDNode instead of "
              "AtomicSDNode for unordered atomic loads and "
              "stores respectively."),
Index: test/CodeGen/X86/atomic-unordered.ll
===================================================================
--- test/CodeGen/X86/atomic-unordered.ll
+++ test/CodeGen/X86/atomic-unordered.ll
@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -O0 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake | FileCheck --check-prefixes=CHECK,CHECK-O0,CHECK-O0-CUR %s
-; RUN: llc -O3 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake | FileCheck --check-prefixes=CHECK,CHECK-O3,CHECK-O3-CUR %s
-; RUN: llc -O0 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake -x86-experimental-unordered-atomic-isel | FileCheck --check-prefixes=CHECK,CHECK-O0,CHECK-O0-EX %s
-; RUN: llc -O3 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake -x86-experimental-unordered-atomic-isel | FileCheck --check-prefixes=CHECK,CHECK-O3,CHECK-O3-EX %s
+; RUN: llc -O0 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake -x86-experimental-unordered-atomic-isel=0 | FileCheck --check-prefixes=CHECK,CHECK-O0,CHECK-O0-CUR %s
+; RUN: llc -O3 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake  -x86-experimental-unordered-atomic-isel=0 | FileCheck --check-prefixes=CHECK,CHECK-O3,CHECK-O3-CUR %s
+; RUN: llc -O0 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake -x86-experimental-unordered-atomic-isel=1 | FileCheck --check-prefixes=CHECK,CHECK-O0,CHECK-O0-EX %s
+; RUN: llc -O3 < %s -mtriple=x86_64-linux-generic -verify-machineinstrs -mcpu=skylake -x86-experimental-unordered-atomic-isel=1 | FileCheck --check-prefixes=CHECK,CHECK-O3,CHECK-O3-EX %s
 
 define i8 @load_i8(i8* %ptr) {
 ; CHECK-LABEL: load_i8: