diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1340,16 +1340,22 @@
 /// least n bits.
 static bool valueCoversEntireFragment(Type *ValTy, DbgVariableIntrinsic *DII) {
   const DataLayout &DL = DII->getModule()->getDataLayout();
-  uint64_t ValueSize = DL.getTypeAllocSizeInBits(ValTy);
-  if (auto FragmentSize = DII->getFragmentSizeInBits())
-    return ValueSize >= *FragmentSize;
+  TypeSize ValueSize = DL.getTypeAllocSizeInBits(ValTy);
+  if (Optional<uint64_t> FragmentSize = DII->getFragmentSizeInBits()) {
+    assert(!ValueSize.isScalable() &&
+           "Fragments don't work on scalable types.");
+    return ValueSize.getFixedSize() >= *FragmentSize;
+  }
   // We can't always calculate the size of the DI variable (e.g. if it is a
   // VLA). Try to use the size of the alloca that the dbg intrinsic describes
   // intead.
   if (DII->isAddressOfVariable())
     if (auto *AI = dyn_cast_or_null<AllocaInst>(DII->getVariableLocation()))
-      if (auto FragmentSize = AI->getAllocationSizeInBits(DL))
-        return ValueSize >= *FragmentSize;
+      if (Optional<TypeSize> FragmentSize = AI->getAllocationSizeInBits(DL)) {
+        assert(ValueSize.isScalable() == FragmentSize->isScalable() &&
+               "Both sizes should agree on the scalable flag.");
+        return TypeSize::isKnownGE(ValueSize, *FragmentSize);
+      }
   // Could not determine size of variable. Conservatively return false.
   return false;
 }
diff --git a/llvm/test/Transforms/InstCombine/debuginfo-scalable-typesize.ll b/llvm/test/Transforms/InstCombine/debuginfo-scalable-typesize.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/debuginfo-scalable-typesize.ll
@@ -0,0 +1,36 @@
+; RUN: opt -instcombine -S < %s 2>%t | FileCheck %s
+; RUN: FileCheck --check-prefix=WARN --allow-empty %s <%t
+
+; This test is defending against a TypeSize message raised in the method
+; `valueCoversEntireFragment` in Local.cpp because of an implicit cast from
+; `TypeSize` to `uint64_t`. This particular TypeSize message only occurred when
+; debug info was available.
+
+; If this check fails please read
+; clang/test/CodeGen/aarch64-sve-intrinsics/README for instructions on
+; how to resolve it.
+; This test must not produce any warnings. Prior to this test being introduced,
+; it produced a warning containing the text "TypeSize is not scalable".
+; WARN-NOT: warning:
+
+; CHECK-LABEL: @debug_local_scalable(
+define <vscale x 2 x double> @debug_local_scalable(<vscale x 2 x double> %tostore) {
+  %vx = alloca <vscale x 2 x double>, align 16
+  call void @llvm.dbg.declare(metadata <vscale x 2 x double>* %vx, metadata !3, metadata !DIExpression()), !dbg !5
+  store <vscale x 2 x double> %tostore, <vscale x 2 x double>* %vx, align 16
+  %ret = call <vscale x 2 x double> @f(<vscale x 2 x double>* %vx)
+  ret <vscale x 2 x double> %ret
+}
+
+declare <vscale x 2 x double> @f(<vscale x 2 x double>*)
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
+!1 = !DIFile(filename: "/tmp/test.c", directory: "/tmp/")
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = !DILocalVariable(scope: !4)
+!4 = distinct !DISubprogram(unit: !0)
+!5 = !DILocation(scope: !4)