diff --git a/llvm/include/llvm/IR/DataLayout.h b/llvm/include/llvm/IR/DataLayout.h
index 2992484c47d06..2acae246c0b1e 100644
--- a/llvm/include/llvm/IR/DataLayout.h
+++ b/llvm/include/llvm/IR/DataLayout.h
@@ -501,10 +501,7 @@ class DataLayout {
   ///
   /// This is the amount that alloca reserves for this type. For example,
   /// returns 12 or 16 for x86_fp80, depending on alignment.
-  TypeSize getTypeAllocSize(Type *Ty) const {
-    // Round up to the next alignment boundary.
-    return alignTo(getTypeStoreSize(Ty), getABITypeAlign(Ty).value());
-  }
+  TypeSize getTypeAllocSize(Type *Ty) const;
 
   /// Returns the offset in bits between successive objects of the
   /// specified type, including alignment padding; always a multiple of 8.
diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
index ee43ad49d0df2..2cf96f8720a05 100644
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -844,6 +844,44 @@ Align DataLayout::getAlignment(Type *Ty, bool abi_or_pref) const {
   }
 }
 
+TypeSize DataLayout::getTypeAllocSize(Type *Ty) const {
+  switch (Ty->getTypeID()) {
+  case Type::ArrayTyID: {
+    // The alignment of the array is the alignment of the element, so there
+    // is no need for further adjustment.
+    auto *ATy = cast<ArrayType>(Ty);
+    return ATy->getNumElements() * getTypeAllocSize(ATy->getElementType());
+  }
+  case Type::StructTyID: {
+    const StructLayout *Layout = getStructLayout(cast<StructType>(Ty));
+    TypeSize Size = Layout->getSizeInBytes();
+
+    if (cast<StructType>(Ty)->isPacked())
+      return Size;
+
+    Align A = std::max(StructABIAlignment, Layout->getAlignment());
+    return alignTo(Size, A.value());
+  }
+  case Type::IntegerTyID: {
+    unsigned BitWidth = Ty->getIntegerBitWidth();
+    TypeSize Size = TypeSize::getFixed(divideCeil(BitWidth, 8));
+    Align A = getIntegerAlignment(BitWidth, /*ABI=*/true);
+    return alignTo(Size, A.value());
+  }
+  case Type::PointerTyID: {
+    unsigned AS = Ty->getPointerAddressSpace();
+    TypeSize Size = TypeSize::getFixed(getPointerSize(AS));
+    return alignTo(Size, getPointerABIAlignment(AS).value());
+  }
+  case Type::TargetExtTyID: {
+    Type *LayoutTy = cast<TargetExtType>(Ty)->getLayoutType();
+    return getTypeAllocSize(LayoutTy);
+  }
+  default:
+    return alignTo(getTypeStoreSize(Ty), getABITypeAlign(Ty).value());
+  }
+}
+
 Align DataLayout::getABITypeAlign(Type *Ty) const {
   return getAlignment(Ty, true);
 }
diff --git a/llvm/test/CodeGen/AArch64/alloca-oversized.ll b/llvm/test/CodeGen/AArch64/alloca-oversized.ll
index e57bbcdf99800..81d301019e7b9 100644
--- a/llvm/test/CodeGen/AArch64/alloca-oversized.ll
+++ b/llvm/test/CodeGen/AArch64/alloca-oversized.ll
@@ -10,10 +10,7 @@ define void @test_oversized(ptr %dst, i32 %cond) {
 ; CHECK-NEXT:    .cfi_offset w30, -8
 ; CHECK-NEXT:    .cfi_offset w29, -16
 ; CHECK-NEXT:    mov x8, sp
-; CHECK-NEXT:    mov x9, #2305843009213693952 // =0x2000000000000000
-; CHECK-NEXT:    sub x8, x8, x9
 ; CHECK-NEXT:    sub x9, x29, #32
-; CHECK-NEXT:    mov sp, x8
 ; CHECK-NEXT:    cmp w1, #0
 ; CHECK-NEXT:    csel x8, x9, x8, eq
 ; CHECK-NEXT:    str x8, [x0]