diff --git a/llvm/lib/Transforms/Utils/Debugify.cpp b/llvm/lib/Transforms/Utils/Debugify.cpp
--- a/llvm/lib/Transforms/Utils/Debugify.cpp
+++ b/llvm/lib/Transforms/Utils/Debugify.cpp
@@ -44,8 +44,9 @@
 
 raw_ostream &dbg() { return Quiet ? nulls() : errs(); }
 
-uint64_t getAllocSizeInBits(Module &M, Type *Ty) {
-  return Ty->isSized() ? M.getDataLayout().getTypeAllocSizeInBits(Ty) : 0;
+TypeSize getAllocSizeInBits(Module &M, Type *Ty) {
+  return Ty->isSized() ? M.getDataLayout().getTypeAllocSizeInBits(Ty)
+                       : TypeSize::getFixed(0);
 }
 
 bool isFunctionSkipped(Function &F) {
@@ -276,7 +277,7 @@
     return false;
 
   Type *Ty = V->getType();
-  uint64_t ValueOperandSize = getAllocSizeInBits(M, Ty);
+  TypeSize ValueOperandSize = getAllocSizeInBits(M, Ty);
   Optional<uint64_t> DbgVarSize = DVI->getFragmentSizeInBits();
   if (!ValueOperandSize || !DbgVarSize)
     return false;
@@ -285,7 +286,7 @@
   if (Ty->isIntegerTy()) {
     auto Signedness = DVI->getVariable()->getSignedness();
     if (Signedness && *Signedness == DIBasicType::Signedness::Signed)
-      HasBadSize = ValueOperandSize < *DbgVarSize;
+      HasBadSize = ValueOperandSize.getFixedSize() < *DbgVarSize;
   } else {
     HasBadSize = ValueOperandSize != *DbgVarSize;
   }
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
@@ -1368,16 +1368,22 @@
 /// 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/debug-declare-no-warnings-on-scalable-vectors.ll b/llvm/test/Transforms/InstCombine/debug-declare-no-warnings-on-scalable-vectors.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/debug-declare-no-warnings-on-scalable-vectors.ll
@@ -0,0 +1,42 @@
+; RUN: opt -mtriple aarch64-gnu-linux -mattr=+sve -instcombine -S < %s 2>%t | FileCheck %s
+; RUN: FileCheck --check-prefix=WARN --allow-empty %s <%t
+
+; If this check fails please read
+; clang/test/CodeGen/aarch64-sve-intrinsics/README for instructions on
+; how to resolve it.
+
+; 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 !5, metadata !DIExpression()), !dbg !15
+  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>*)
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 12.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "/tmp/test.c", directory: "/tmp/")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !DILocalVariable(name: "vx", scope: !6, file: !7, line: 26, type: !8)
+!6 = distinct !DISubprogram(name: "debug_local_scalable", scope: null, file: !1, line: 25, scopeLine: 25, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!7 = !DIFile(filename: "test.c", directory: "/tmp/")
+!8 = !DIDerivedType(tag: DW_TAG_typedef, name: "svfloat64_t", file: !9, line: 56, baseType: !10)
+!9 = !DIFile(filename: "arm_sve.h", directory: "/tmp/")
+!10 = !DIDerivedType(tag: DW_TAG_typedef, name: "__SVFloat64_t", file: !1, baseType: !11)
+!11 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, flags: DIFlagVector, elements: !13)
+!12 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
+!13 = !{!14}
+!14 = !DISubrange(lowerBound: 0, upperBound: !DIExpression(DW_OP_constu, 1, DW_OP_bregx, 46, 0, DW_OP_mul, DW_OP_constu, 1, DW_OP_minus))
+!15 = !DILocation(line: 26, column: 15, scope: !6)