diff --git a/llvm/lib/Target/ARM/ARMISelLowering.h b/llvm/lib/Target/ARM/ARMISelLowering.h
--- a/llvm/lib/Target/ARM/ARMISelLowering.h
+++ b/llvm/lib/Target/ARM/ARMISelLowering.h
@@ -633,6 +633,9 @@
     Value *emitStoreConditional(IRBuilderBase &Builder, Value *Val, Value *Addr,
                                 AtomicOrdering Ord) const override;
 
+    Value *castToInt8PtrInDefaultAddressSpace(IRBuilderBase &Builder, Module &M,
+                                              Value *Addr) const;
+
     void
     emitAtomicCmpXchgNoStoreLLBalance(IRBuilderBase &Builder) const override;
 
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -19615,6 +19615,25 @@
   return !Subtarget->hasMinSize() || Subtarget->isTargetWindows();
 }
 
+Value *
+ARMTargetLowering::castToInt8PtrInDefaultAddressSpace(IRBuilderBase &Builder,
+                                                      Module &M, Value *Addr) const {
+  unsigned AddressSpace = cast<PointerType>(Addr->getType())->getAddressSpace();
+  Addr = Builder.CreateBitCast(
+      Addr, Type::getInt8PtrTy(M.getContext(), AddressSpace));
+
+  PointerType *Int8PtrTy = Type::getInt8PtrTy(M.getContext());
+  if (AddressSpace != Int8PtrTy->getAddressSpace()) {
+    // The pointer does not point to the default address space.
+    // Perform an address space cast to the default address space.
+    //
+    // We assume that atomic operations have the same semantics on ARM
+    // irrespective of the address space.
+    Addr = Builder.CreateAddrSpaceCast(Addr, Int8PtrTy);
+  }
+  return Addr;
+}
+
 Value *ARMTargetLowering::emitLoadLinked(IRBuilderBase &Builder, Value *Addr,
                                          AtomicOrdering Ord) const {
   Module *M = Builder.GetInsertBlock()->getParent()->getParent();
@@ -19629,7 +19648,7 @@
         IsAcquire ? Intrinsic::arm_ldaexd : Intrinsic::arm_ldrexd;
     Function *Ldrex = Intrinsic::getDeclaration(M, Int);
 
-    Addr = Builder.CreateBitCast(Addr, Type::getInt8PtrTy(M->getContext()));
+    Addr = castToInt8PtrInDefaultAddressSpace(Builder, *M, Addr);
     Value *LoHi = Builder.CreateCall(Ldrex, Addr, "lohi");
 
     Value *Lo = Builder.CreateExtractValue(LoHi, 0, "lo");
@@ -19678,7 +19697,8 @@
     Value *Hi = Builder.CreateTrunc(Builder.CreateLShr(Val, 32), Int32Ty, "hi");
     if (!Subtarget->isLittle())
       std::swap(Lo, Hi);
-    Addr = Builder.CreateBitCast(Addr, Type::getInt8PtrTy(M->getContext()));
+
+    Addr = castToInt8PtrInDefaultAddressSpace(Builder, *M, Addr);
     return Builder.CreateCall(Strex, {Lo, Hi, Addr});
   }
 
diff --git a/llvm/test/CodeGen/ARM/atomic-i64-other-address-space.ll b/llvm/test/CodeGen/ARM/atomic-i64-other-address-space.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/atomic-i64-other-address-space.ll
@@ -0,0 +1,69 @@
+; RUN: llc < %s -mtriple=armv6k-linux-gnueabihf | FileCheck %s --check-prefixes=ARMV6K
+; RUN: llc < %s -mtriple=armv7-linux-gnueabihf | FileCheck %s --check-prefixes=ARMV7
+; RUN: llc < %s -mtriple=thumbv7-linux-gnueabihf | FileCheck %s --check-prefixes=THUMBV7
+
+;THUMBV7: atomic_load_i64_other_address_space:
+;THUMBV7: @ %bb.0: @ %load_entry
+;THUMBV7-NEXT:    ldrexd r0, r1, [r0]
+;THUMBV7-NEXT:    clrex
+;THUMBV7-NEXT:    dmb ish
+;THUMBV7-NEXT:    bx lr
+;THUMBV7: atomic_store_i64_other_address_space:
+;THUMBV7: @ %bb.0: @ %store_entry
+;THUMBV7-NEXT:    dmb ish
+;THUMBV7-NEXT:.LBB1_1: @ %atomicrmw.start
+;THUMBV7:         ldrexd r1, r12, [r0]
+;THUMBV7-NEXT:    strexd r1, r2, r3, [r0]
+;THUMBV7-NEXT:    cmp r1, #0
+;THUMBV7-NEXT:    bne .LBB1_1
+;THUMBV7-NEXT:@ %bb.2: @ %atomicrmw.end
+;THUMBV7-NEXT:    bx lr
+
+;ARMV6K: atomic_load_i64_other_address_space:
+;ARMV6K: @ %bb.0: @ %load_entry
+;ARMV6K-NEXT:     ldrexd r0, r1, [r0]
+;ARMV6K-NEXT:     mov r2, #0
+;ARMV6K-NEXT:     mcr p15, #0, r2, c7, c10, #5
+;ARMV6K-NEXT:     bx lr
+;ARMV6K: atomic_store_i64_other_address_space:
+;ARMV6K: @ %bb.0: @ %store_entry
+;ARMV6K:          push {r4, r5, r11, lr}
+;ARMV6K:          mov r1, #0
+;ARMV6K:          mcr p15, #0, r1, c7, c10, #5
+;ARMV6K-NEXT: .LBB1_1: @ %atomicrmw.start
+;ARMV6K:          ldrexd r4, r5, [r0]
+;ARMV6K-NEXT:     strexd r1, r2, r3, [r0]
+;ARMV6K-NEXT:     cmp r1, #0
+;ARMV6K-NEXT:     bne .LBB1_1
+;ARMV6K-NEXT: @ %bb.2: @ %atomicrmw.end
+;ARMV6K-NEXT:     pop {r4, r5, r11, pc}
+
+; ARMV7: atomic_load_i64_other_address_space:
+; ARMV7: @ %bb.0: @ %load_entry
+; ARMV7-NEXT:    ldrexd r0, r1, [r0]
+; ARMV7-NEXT:    clrex
+; ARMV7-NEXT:    dmb ish
+; ARMV7-NEXT:    bx lr
+; ARMV7: atomic_store_i64_other_address_space:
+; ARMV7: @ %bb.0: @ %store_entry
+; ARMV7:         push {r4, r5, r11, lr}
+; ARMV7:         dmb ish
+; ARMV7: .LBB1_1: @ %atomicrmw.start
+; ARMV7:         ldrexd r4, r5, [r0]
+; ARMV7-NEXT:    strexd r1, r2, r3, [r0]
+; ARMV7-NEXT:    cmp r1, #0
+; ARMV7-NEXT:    bne .LBB1_1
+; ARMV7-NEXT: @ %bb.2: @ %atomicrmw.end
+; ARMV7-NEXT:    pop {r4, r5, r11, pc}
+
+define i64 @atomic_load_i64_other_address_space(i64 addrspace(1)* align 8 %ptr) {
+load_entry:
+    %val = load atomic i64, i64 addrspace(1)* %ptr acquire, align 8
+    ret i64 %val
+}
+
+define void @atomic_store_i64_other_address_space(i64 addrspace(1)* align 8 %ptr, i64 %value) {
+store_entry:
+    store atomic i64 %value, i64 addrspace(1)* %ptr release, align 8
+    ret void
+}