Index: llvm/include/llvm/IR/Instructions.h
===================================================================
--- llvm/include/llvm/IR/Instructions.h
+++ llvm/include/llvm/IR/Instructions.h
@@ -105,6 +105,11 @@
     return cast<PointerType>(Instruction::getType());
   }
 
+  /// Return the address space for the allocation.
+  unsigned getAddressSpace() const {
+    return getType()->getAddressSpace();
+  }
+
   /// Get allocation size in bits. Returns None if size can't be determined,
   /// e.g. in case of a VLA.
   Optional<TypeSize> getAllocationSizeInBits(const DataLayout &DL) const;
Index: llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -157,7 +157,7 @@
     Amt = Builder.CreateAdd(Amt, Off);
   }
 
-  AllocaInst *New = Builder.CreateAlloca(CastElTy, Amt);
+  AllocaInst *New = Builder.CreateAlloca(CastElTy, AI.getAddressSpace(), Amt);
   New->setAlignment(AI.getAlign());
   New->takeName(&AI);
   New->setUsedWithInAlloca(AI.isUsedWithInAlloca());
Index: llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -183,7 +183,8 @@
   if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
     if (C->getValue().getActiveBits() <= 64) {
       Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
-      AllocaInst *New = IC.Builder.CreateAlloca(NewTy, nullptr, AI.getName());
+      AllocaInst *New = IC.Builder.CreateAlloca(NewTy, AI.getAddressSpace(),
+                                                nullptr, AI.getName());
       New->setAlignment(AI.getAlign());
 
       // Scan to the end of the allocation instructions, to skip over a block of
@@ -199,21 +200,13 @@
       Type *IdxTy = IC.getDataLayout().getIntPtrType(AI.getType());
       Value *NullIdx = Constant::getNullValue(IdxTy);
       Value *Idx[2] = {NullIdx, NullIdx};
-      Instruction *NewI = GetElementPtrInst::CreateInBounds(
+      Instruction *GEP = GetElementPtrInst::CreateInBounds(
           NewTy, New, Idx, New->getName() + ".sub");
-      IC.InsertNewInstBefore(NewI, *It);
-
-      // Gracefully handle allocas in other address spaces.
-      if (AI.getType()->getPointerAddressSpace() !=
-          NewI->getType()->getPointerAddressSpace()) {
-        NewI =
-            CastInst::CreatePointerBitCastOrAddrSpaceCast(NewI, AI.getType());
-        IC.InsertNewInstBefore(NewI, *It);
-      }
+      IC.InsertNewInstBefore(GEP, *It);
 
       // Now make everything use the getelementptr instead of the original
       // allocation.
-      return IC.replaceInstUsesWith(AI, NewI);
+      return IC.replaceInstUsesWith(AI, GEP);
     }
   }
 
Index: llvm/test/Transforms/InstCombine/alloca-in-non-alloca-as.ll
===================================================================
--- llvm/test/Transforms/InstCombine/alloca-in-non-alloca-as.ll
+++ llvm/test/Transforms/InstCombine/alloca-in-non-alloca-as.ll
@@ -11,11 +11,9 @@
 define weak amdgpu_kernel void @__omp_offloading_802_ea0109_main_l8(i32* %a) {
 ; CHECK-LABEL: @__omp_offloading_802_ea0109_main_l8(
 ; CHECK-NEXT:  .master:
-; CHECK-NEXT:    [[TMP0:%.*]] = alloca i32*, align 1, addrspace(5)
-; CHECK-NEXT:    [[DOTSUB:%.*]] = bitcast i32* addrspace(5)* [[TMP0]] to i8 addrspace(5)*
-; CHECK-NEXT:    [[TMP1:%.*]] = addrspacecast i8 addrspace(5)* [[DOTSUB]] to i8*
-; CHECK-NEXT:    [[A_ON_STACK:%.*]] = addrspacecast i32* addrspace(5)* [[TMP0]] to i32**
-; CHECK-NEXT:    call void @use(i8* [[TMP1]], i32** [[A_ON_STACK]])
+; CHECK-NEXT:    [[TMP0:%.*]] = alloca i32*, align 1
+; CHECK-NEXT:    [[DOTSUB:%.*]] = bitcast i32** [[TMP0]] to i8*
+; CHECK-NEXT:    call void @use(i8* [[DOTSUB]], i32** [[TMP0]])
 ; CHECK-NEXT:    ret void
 ;
 .master:
@@ -31,10 +29,8 @@
 define void @spam(i64* %arg1) {
 ; CHECK-LABEL: @spam(
 ; CHECK-NEXT:  bb:
-; CHECK-NEXT:    [[ALLOCA1:%.*]] = alloca [0 x [30 x %struct.widget]], align 16, addrspace(5)
-; CHECK-NEXT:    [[ALLOCA1_SUB:%.*]] = getelementptr inbounds [0 x [30 x %struct.widget]], [0 x [30 x %struct.widget]] addrspace(5)* [[ALLOCA1]], i32 0, i32 0
-; CHECK-NEXT:    [[TMP0:%.*]] = addrspacecast [30 x %struct.widget] addrspace(5)* [[ALLOCA1_SUB]] to [30 x %struct.widget]*
-; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds [30 x %struct.widget], [30 x %struct.widget]* [[TMP0]], i64 0, i64 0
+; CHECK-NEXT:    [[ALLOCA1:%.*]] = alloca [0 x [30 x %struct.widget]], align 16
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds [0 x [30 x %struct.widget]], [0 x [30 x %struct.widget]]* [[ALLOCA1]], i64 0, i64 0, i64 0
 ; CHECK-NEXT:    call void @zot(%struct.widget* [[GEP]])
 ; CHECK-NEXT:    ret void
 ;