Index: llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1108,8 +1108,14 @@
     uint64_t AlignedSize = alignTo(Size, Mapping.getAllocaAlignment());
     AI->setAlignment(std::max(AI->getAlignment(), 16u));
     if (Size != AlignedSize) {
+      Type *AllocatedType = AI->getAllocatedType();
+      if (AI->isArrayAllocation()) {
+        uint64_t ArraySize =
+            cast<ConstantInt>(AI->getArraySize())->getZExtValue();
+        AllocatedType = ArrayType::get(AllocatedType, ArraySize);
+      }
       Type *TypeWithPadding = StructType::get(
-          AI->getAllocatedType(), ArrayType::get(Int8Ty, AlignedSize - Size));
+          AllocatedType, ArrayType::get(Int8Ty, AlignedSize - Size));
       auto *NewAI = new AllocaInst(
           TypeWithPadding, AI->getType()->getAddressSpace(), nullptr, "", AI);
       NewAI->takeName(AI);
@@ -1117,10 +1123,8 @@
       NewAI->setUsedWithInAlloca(AI->isUsedWithInAlloca());
       NewAI->setSwiftError(AI->isSwiftError());
       NewAI->copyMetadata(*AI);
-      Value *Zero = ConstantInt::get(Int32Ty, 0);
-      auto *GEP = GetElementPtrInst::Create(TypeWithPadding, NewAI,
-                                            {Zero, Zero}, "", AI);
-      AI->replaceAllUsesWith(GEP);
+      auto *Bitcast = new BitCastInst(NewAI, AI->getType(), "", AI);
+      AI->replaceAllUsesWith(Bitcast);
       AllocaToPaddedAllocaMap[AI] = NewAI;
     }
   }
Index: llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca-array.ll
===================================================================
--- llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca-array.ll
+++ llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca-array.ll
@@ -0,0 +1,15 @@
+; RUN: opt < %s -hwasan -S | FileCheck %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-android"
+
+declare void @use(i8*, i8*)
+
+define void @test_alloca() sanitize_hwaddress {
+  ; CHECK: alloca { [4 x i8], [12 x i8] }, align 16
+  %x = alloca i8, i64 4
+  ; CHECK: alloca i8, i64 16, align 16
+  %y = alloca i8, i64 16
+  call void @use(i8* %x, i8* %y)
+  ret void
+}
Index: llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca-with-calls.ll
===================================================================
--- llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca-with-calls.ll
+++ llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca-with-calls.ll
@@ -9,10 +9,10 @@
 
 define void @test_alloca() sanitize_hwaddress {
 ; CHECK-LABEL: @test_alloca(
-; CHECK: %[[GEP:[^ ]*]] = getelementptr { i32, [12 x i8] }, { i32, [12 x i8] }* %x, i32 0, i32 0
+; CHECK: %[[BC:[^ ]*]] = bitcast { i32, [12 x i8] }* %x to i32*
 ; CHECK: %[[T1:[^ ]*]] = call i8 @__hwasan_generate_tag()
 ; CHECK: %[[A:[^ ]*]] = zext i8 %[[T1]] to i64
-; CHECK: %[[B:[^ ]*]] = ptrtoint i32* %[[GEP]] to i64
+; CHECK: %[[B:[^ ]*]] = ptrtoint i32* %[[BC]] to i64
 ; CHECK: %[[C:[^ ]*]] = shl i64 %[[A]], 56
 ; CHECK: or i64 %[[B]], %[[C]]
 
Index: llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca.ll
===================================================================
--- llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca.ll
+++ llvm/trunk/test/Instrumentation/HWAddressSanitizer/alloca.ll
@@ -17,28 +17,28 @@
 ; CHECK: %[[BASE_TAG:[^ ]*]] = xor i64 %[[A]], %[[B]]
 
 ; CHECK: %[[X:[^ ]*]] = alloca { i32, [12 x i8] }, align 16
-; CHECK: %[[X_GEP:[^ ]*]] = getelementptr { i32, [12 x i8] }, { i32, [12 x i8] }* %[[X]], i32 0, i32 0
+; CHECK: %[[X_BC:[^ ]*]] = bitcast { i32, [12 x i8] }* %[[X]] to i32*
 ; CHECK: %[[X_TAG:[^ ]*]] = xor i64 %[[BASE_TAG]], 0
-; CHECK: %[[X1:[^ ]*]] = ptrtoint i32* %[[X_GEP]] to i64
+; CHECK: %[[X1:[^ ]*]] = ptrtoint i32* %[[X_BC]] to i64
 ; CHECK: %[[C:[^ ]*]] = shl i64 %[[X_TAG]], 56
 ; CHECK: %[[D:[^ ]*]] = or i64 %[[X1]], %[[C]]
 ; CHECK: %[[X_HWASAN:[^ ]*]] = inttoptr i64 %[[D]] to i32*
 
 ; CHECK: %[[X_TAG2:[^ ]*]] = trunc i64 %[[X_TAG]] to i8
-; CHECK: %[[E:[^ ]*]] = ptrtoint i32* %[[X_GEP]] to i64
+; CHECK: %[[E:[^ ]*]] = ptrtoint i32* %[[X_BC]] to i64
 ; CHECK: %[[F:[^ ]*]] = lshr i64 %[[E]], 4
 ; DYNAMIC-SHADOW: %[[X_SHADOW:[^ ]*]] = getelementptr i8, i8* %.hwasan.shadow, i64 %[[F]]
 ; ZERO-BASED-SHADOW: %[[X_SHADOW:[^ ]*]] = inttoptr i64 %[[F]] to i8*
 ; CHECK: %[[X_SHADOW_GEP:[^ ]*]] = getelementptr i8, i8* %[[X_SHADOW]], i32 0
 ; CHECK: store i8 4, i8* %[[X_SHADOW_GEP]]
-; CHECK: %[[X_I8:[^ ]*]] = bitcast i32* %[[X_GEP]] to i8*
+; CHECK: %[[X_I8:[^ ]*]] = bitcast i32* %[[X_BC]] to i8*
 ; CHECK: %[[X_I8_GEP:[^ ]*]] = getelementptr i8, i8* %[[X_I8]], i32 15
 ; CHECK: store i8 %[[X_TAG2]], i8* %[[X_I8_GEP]]
 ; CHECK: call void @use32(i32* nonnull %[[X_HWASAN]])
 
 ; UAR-TAGS: %[[BASE_TAG_COMPL:[^ ]*]] = xor i64 %[[BASE_TAG]], 255
 ; UAR-TAGS: %[[X_TAG_UAR:[^ ]*]] = trunc i64 %[[BASE_TAG_COMPL]] to i8
-; CHECK: %[[E2:[^ ]*]] = ptrtoint i32* %[[X_GEP]] to i64
+; CHECK: %[[E2:[^ ]*]] = ptrtoint i32* %[[X_BC]] to i64
 ; CHECK: %[[F2:[^ ]*]] = lshr i64 %[[E2]], 4
 ; DYNAMIC-SHADOW: %[[X_SHADOW2:[^ ]*]] = getelementptr i8, i8* %.hwasan.shadow, i64 %[[F2]]
 ; ZERO-BASED-SHADOW: %[[X_SHADOW2:[^ ]*]] = inttoptr i64 %[[F2]] to i8*
Index: llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel-alloca.ll
===================================================================
--- llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel-alloca.ll
+++ llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel-alloca.ll
@@ -15,9 +15,9 @@
 ; CHECK: %[[BASE_TAG:[^ ]*]] = xor i64 %[[A]], %[[B]]
 
 ; CHECK: %[[X:[^ ]*]] = alloca { i32, [12 x i8] }, align 16
-; CHECK: %[[X_GEP:[^ ]*]] = getelementptr { i32, [12 x i8] }, { i32, [12 x i8] }* %[[X]], i32 0, i32 0
+; CHECK: %[[X_BC:[^ ]*]] = bitcast { i32, [12 x i8] }* %[[X]] to i32*
 ; CHECK: %[[X_TAG:[^ ]*]] = xor i64 %[[BASE_TAG]], 0
-; CHECK: %[[X1:[^ ]*]] = ptrtoint i32* %[[X_GEP]] to i64
+; CHECK: %[[X1:[^ ]*]] = ptrtoint i32* %[[X_BC]] to i64
 ; CHECK: %[[C:[^ ]*]] = shl i64 %[[X_TAG]], 56
 ; CHECK: %[[D:[^ ]*]] = or i64 %[[C]], 72057594037927935
 ; CHECK: %[[E:[^ ]*]] = and i64 %[[X1]], %[[D]]