diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 06cccab322100..170e267356d58 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -4696,6 +4696,19 @@ struct VarArgHelperBase : public VarArgHelper {
                               "_msarg_va_o");
   }
 
+  void CleanUnusedTLS(IRBuilder<> &IRB, Value *ShadowBase,
+                      unsigned BaseOffset) {
+    // The tails of __msan_va_arg_tls is not large enough to fit full
+    // value shadow, but it will be copied to backup anyway. Make it
+    // clean.
+    if (BaseOffset >= kParamTLSSize)
+      return;
+    Value *TailSize =
+        ConstantInt::getSigned(IRB.getInt32Ty(), kParamTLSSize - BaseOffset);
+    IRB.CreateMemSet(ShadowBase, ConstantInt::getNullValue(IRB.getInt8Ty()),
+                     TailSize, Align(8));
+  }
+
   void unpoisonVAListTagForInst(IntrinsicInst &I) {
     IRBuilder<> IRB(&I);
     Value *VAListTag = I.getArgOperand(0);
@@ -4779,23 +4792,6 @@ struct VarArgAMD64Helper : public VarArgHelperBase {
     unsigned OverflowOffset = AMD64FpEndOffset;
     const DataLayout &DL = F.getParent()->getDataLayout();
 
-    auto CleanUnusedTLS = [&](Value *ShadowBase, unsigned BaseOffset) {
-      // Make sure we don't overflow __msan_va_arg_tls.
-      if (OverflowOffset <= kParamTLSSize)
-        return false; // Not needed, end is not reacheed.
-
-      // The tails of __msan_va_arg_tls is not large enough to fit full
-      // value shadow, but it will be copied to backup anyway. Make it
-      // clean.
-      if (BaseOffset < kParamTLSSize) {
-        Value *TailSize = ConstantInt::getSigned(IRB.getInt32Ty(),
-                                                 kParamTLSSize - BaseOffset);
-        IRB.CreateMemSet(ShadowBase, ConstantInt::getNullValue(IRB.getInt8Ty()),
-                         TailSize, Align(8));
-      }
-      return true; // Incomplete
-    };
-
     for (const auto &[ArgNo, A] : llvm::enumerate(CB.args())) {
       bool IsFixed = ArgNo < CB.getFunctionType()->getNumParams();
       bool IsByVal = CB.paramHasAttr(ArgNo, Attribute::ByVal);
@@ -4817,8 +4813,10 @@ struct VarArgAMD64Helper : public VarArgHelperBase {
           OriginBase = getOriginPtrForVAArgument(IRB, OverflowOffset);
         OverflowOffset += AlignedSize;
 
-        if (CleanUnusedTLS(ShadowBase, BaseOffset))
+        if (OverflowOffset > kParamTLSSize) {
+          CleanUnusedTLS(IRB, ShadowBase, BaseOffset);
           continue; // We have no space to copy shadow there.
+        }
 
         Value *ShadowPtr, *OriginPtr;
         std::tie(ShadowPtr, OriginPtr) =
@@ -4863,8 +4861,11 @@ struct VarArgAMD64Helper : public VarArgHelperBase {
             OriginBase = getOriginPtrForVAArgument(IRB, OverflowOffset);
           }
           OverflowOffset += AlignedSize;
-          if (CleanUnusedTLS(ShadowBase, BaseOffset))
-            continue; // We have no space to copy shadow there.
+          if (OverflowOffset > kParamTLSSize) {
+            // We have no space to copy shadow there.
+            CleanUnusedTLS(IRB, ShadowBase, BaseOffset);
+            continue;
+          }
         }
         // Take fixed arguments into account for GpOffset and FpOffset,
         // but don't actually store shadows for them.
@@ -5118,17 +5119,21 @@ struct VarArgAArch64Helper : public VarArgHelperBase {
         if (IsFixed)
           continue;
         uint64_t ArgSize = DL.getTypeAllocSize(A->getType());
-        Base = getShadowPtrForVAArgument(A->getType(), IRB, OverflowOffset,
-                                         alignTo(ArgSize, 8));
-        OverflowOffset += alignTo(ArgSize, 8);
+        uint64_t AlignedSize = alignTo(ArgSize, 8);
+        unsigned BaseOffset = OverflowOffset;
+        Base = getShadowPtrForVAArgument(A->getType(), IRB, BaseOffset);
+        OverflowOffset += AlignedSize;
+        if (OverflowOffset > kParamTLSSize) {
+          // We have no space to copy shadow there.
+          CleanUnusedTLS(IRB, Base, BaseOffset);
+          continue;
+        }
         break;
       }
       // Count Gp/Vr fixed arguments to their respective offsets, but don't
       // bother to actually store a shadow.
       if (IsFixed)
         continue;
-      if (!Base)
-        continue;
       IRB.CreateAlignedStore(MSV.getShadow(A), Base, kShadowTLSAlignment);
     }
     Constant *OverflowSize =
diff --git a/llvm/test/Instrumentation/MemorySanitizer/AArch64/vararg_shadow.ll b/llvm/test/Instrumentation/MemorySanitizer/AArch64/vararg_shadow.ll
index 66f4d61f444f3..ff9d4eea1596b 100644
--- a/llvm/test/Instrumentation/MemorySanitizer/AArch64/vararg_shadow.ll
+++ b/llvm/test/Instrumentation/MemorySanitizer/AArch64/vararg_shadow.ll
@@ -1859,6 +1859,7 @@ define linkonce_odr dso_local void @_Z4test2I11LongDouble4EvT_([4 x fp128] align
 ; CHECK-NEXT:    store [4 x i128] [[TMP35]], ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_va_arg_tls to i64), i64 576) to ptr), align 8
 ; CHECK-NEXT:    store [4 x i128] [[TMP35]], ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_va_arg_tls to i64), i64 640) to ptr), align 8
 ; CHECK-NEXT:    store [4 x i128] [[TMP35]], ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_va_arg_tls to i64), i64 704) to ptr), align 8
+; CHECK-NEXT:    call void @llvm.memset.p0.i32(ptr align 8 inttoptr (i64 add (i64 ptrtoint (ptr @__msan_va_arg_tls to i64), i64 768) to ptr), i8 0, i32 32, i1 false)
 ; CHECK-NEXT:    store i64 1280, ptr @__msan_va_arg_overflow_size_tls, align 8
 ; CHECK-NEXT:    call void ([4 x fp128], i32, ...) @_Z5test2I11LongDouble4EvT_iz([4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], i32 noundef 20, [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]], [4 x fp128] alignstack(16) [[DOTFCA_3_INSERT121]])
 ; CHECK-NEXT:    ret void