Index: lib/Target/Mips/MipsISelLowering.cpp
===================================================================
--- lib/Target/Mips/MipsISelLowering.cpp
+++ lib/Target/Mips/MipsISelLowering.cpp
@@ -1407,7 +1412,7 @@
 
   MachineFunction *MF = BB->getParent();
   MachineRegisterInfo &RegInfo = MF->getRegInfo();
-  const TargetRegisterClass *RC = getRegClassFor(MVT::i32);
+  const TargetRegisterClass *RC = Subtarget.isABI_N64() ? getRegClassFor(MVT::i64) : getRegClassFor(MVT::i32);
   const TargetInstrInfo *TII = Subtarget.getInstrInfo();
   DebugLoc DL = MI->getDebugLoc();
 
Index: test/CodeGen/Mips/at1.ll
===================================================================
--- test/CodeGen/Mips/at1.ll
+++ test/CodeGen/Mips/at1.ll
@@ -0,0 +1,16 @@
+; RUN: llc %s   -march=mips64el -mcpu=mips64r2 < %s -filetype=obj -o - \
+; RUN:   | llvm-objdump -mattr=+mips64r2 -d - | FileCheck %s -implicit-check-not=sw
+
+@_ZZ14InitializeOncevE5array = global [1 x i32*] zeroinitializer, align 8
+@_ZGVZ14InitializeOncevE5array = global i64 0, align 8
+
+define void @_Z14InitializeOncev() #0 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+  %exn.slot = alloca i8*
+  %ehselector.slot = alloca i32
+  %0 = load atomic i8, i8* bitcast (i64* @_ZGVZ14InitializeOncevE5array to i8*) acquire, align 8
+  ret void
+}
+
+
+declare i32 @__gxx_personality_v0(...)