diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -106,7 +106,7 @@
 
   /// Get allocation size in bits. Returns None if size can't be determined,
   /// e.g. in case of a VLA.
-  Optional<uint64_t> getAllocationSizeInBits(const DataLayout &DL) const;
+  Optional<TypeSize> getAllocationSizeInBits(const DataLayout &DL) const;
 
   /// Return the type that is being allocated by the instruction.
   Type *getAllocatedType() const { return AllocatedType; }
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -49,13 +49,14 @@
 //                            AllocaInst Class
 //===----------------------------------------------------------------------===//
 
-Optional<uint64_t>
+Optional<TypeSize>
 AllocaInst::getAllocationSizeInBits(const DataLayout &DL) const {
-  uint64_t Size = DL.getTypeAllocSizeInBits(getAllocatedType());
+  TypeSize Size = DL.getTypeAllocSizeInBits(getAllocatedType());
   if (isArrayAllocation()) {
     auto *C = dyn_cast<ConstantInt>(getArraySize());
     if (!C)
       return None;
+    assert(!Size.isScalable() && "Array elements cannot have a scalable size");
     Size *= C->getZExtValue();
   }
   return Size;
diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -576,9 +576,10 @@
         StackLifetimeAnalyzer.getLiveRange(AI2));
   };
   auto GetAllocaSize = [&](const AllocaInfo &A) {
-    Optional<uint64_t> RetSize = A.Alloca->getAllocationSizeInBits(DL);
-    assert(RetSize && "We can't handle scalable type now.\n");
-    return RetSize.getValue();
+    Optional<TypeSize> RetSize = A.Alloca->getAllocationSizeInBits(DL);
+    assert(RetSize && "Variable Length Arrays (VLA) are not supported.\n");
+    assert(!RetSize->isScalable() && "Scalable vectors are not yet supported");
+    return RetSize->getFixedSize();
   };
   // Put larger allocas in the front. So the larger allocas have higher
   // priority to merge, which can save more space potentially. Also each
diff --git a/llvm/unittests/IR/InstructionsTest.cpp b/llvm/unittests/IR/InstructionsTest.cpp
--- a/llvm/unittests/IR/InstructionsTest.cpp
+++ b/llvm/unittests/IR/InstructionsTest.cpp
@@ -1400,5 +1400,45 @@
   ASSERT_EQ(ProfWeight, UINT32_MAX);
 }
 
+TEST(InstructionsTest, AllocaInst) {
+  LLVMContext Ctx;
+  std::unique_ptr<Module> M = parseIR(Ctx, R"(
+      %T = type { i64, [3 x i32]}
+      define void @f(i32 %n) {
+      entry:
+        %A = alloca i32, i32 1
+        %B = alloca i32, i32 4
+        %C = alloca i32, i32 %n
+        %D = alloca <8 x double>
+        %E = alloca <vscale x 8 x double>
+        %F = alloca [2 x half]
+        %G = alloca [2 x [3 x i128]]
+        %H = alloca %T
+        ret void
+      }
+    )");
+  const DataLayout &DL = M->getDataLayout();
+  ASSERT_TRUE(M);
+  Function *Fun = cast<Function>(M->getNamedValue("f"));
+  BasicBlock &BB = Fun->front();
+  auto It = BB.begin();
+  AllocaInst &A = cast<AllocaInst>(*It++);
+  AllocaInst &B = cast<AllocaInst>(*It++);
+  AllocaInst &C = cast<AllocaInst>(*It++);
+  AllocaInst &D = cast<AllocaInst>(*It++);
+  AllocaInst &E = cast<AllocaInst>(*It++);
+  AllocaInst &F = cast<AllocaInst>(*It++);
+  AllocaInst &G = cast<AllocaInst>(*It++);
+  AllocaInst &H = cast<AllocaInst>(*It++);
+  EXPECT_EQ(A.getAllocationSizeInBits(DL), TypeSize::getFixed(32));
+  EXPECT_EQ(B.getAllocationSizeInBits(DL), TypeSize::getFixed(128));
+  EXPECT_FALSE(C.getAllocationSizeInBits(DL));
+  EXPECT_EQ(D.getAllocationSizeInBits(DL), TypeSize::getFixed(512));
+  EXPECT_EQ(E.getAllocationSizeInBits(DL), TypeSize::getScalable(512));
+  EXPECT_EQ(F.getAllocationSizeInBits(DL), TypeSize::getFixed(32));
+  EXPECT_EQ(G.getAllocationSizeInBits(DL), TypeSize::getFixed(768));
+  EXPECT_EQ(H.getAllocationSizeInBits(DL), TypeSize::getFixed(160));
+}
+
 } // end anonymous namespace
 } // end namespace llvm