diff --git a/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h b/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h
index e880b6227ef0b..4c17e8dcc41a6 100644
--- a/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h
+++ b/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h
@@ -35,6 +35,7 @@ namespace llvm {
 class Argument;
 class BasicBlock;
 class BranchProbabilityInfo;
+class DbgDeclareInst;
 class Function;
 class Instruction;
 class MachineFunction;
@@ -187,6 +188,10 @@ class FunctionLoweringInfo {
   /// SelectionDAGISel::PrepareEHLandingPad().
   unsigned ExceptionPointerVirtReg, ExceptionSelectorVirtReg;
 
+  /// Collection of dbg.declare instructions handled after argument
+  /// lowering and before ISel proper.
+  SmallPtrSet<const DbgDeclareInst *, 8> PreprocessedDbgDeclares;
+
   /// set - Initialize this FunctionLoweringInfo with the given Function
   /// and its associated MachineFunction.
   ///
diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index f8fde640a3f27..3e6b6798dd230 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1208,6 +1208,9 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
       return true;
     }
 
+    if (FuncInfo.PreprocessedDbgDeclares.contains(DI))
+      return true;
+
     const Value *Address = DI->getAddress();
     if (!Address || isa<UndefValue>(Address)) {
       LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI
@@ -1215,13 +1218,6 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
       return true;
     }
 
-    // Byval arguments with frame indices were already handled after argument
-    // lowering and before isel.
-    const auto *Arg =
-        dyn_cast<Argument>(Address->stripInBoundsConstantOffsets());
-    if (Arg && FuncInfo.getArgumentFrameIndex(Arg) != INT_MAX)
-      return true;
-
     std::optional<MachineOperand> Op;
     if (Register Reg = lookUpRegForValue(Address))
       Op = MachineOperand::CreateReg(Reg, false);
diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index df236c503e4b1..f5569ffdac3a8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -348,6 +348,7 @@ void FunctionLoweringInfo::clear() {
   StatepointStackSlots.clear();
   StatepointRelocationMaps.clear();
   PreferredExtendType.clear();
+  PreprocessedDbgDeclares.clear();
 }
 
 /// CreateReg - Allocate a single virtual register for the given type.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index df6b24f86941b..f4ca34ebfd582 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6125,12 +6125,14 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
     return;
   }
   case Intrinsic::dbg_declare: {
+    const auto &DI = cast<DbgDeclareInst>(I);
     // Debug intrinsics are handled separately in assignment tracking mode.
-    if (AssignmentTrackingEnabled)
+    // Some intrinsics are handled right after Argument lowering.
+    if (AssignmentTrackingEnabled ||
+        FuncInfo.PreprocessedDbgDeclares.count(&DI))
       return;
     // Assume dbg.declare can not currently use DIArgList, i.e.
     // it is non-variadic.
-    const auto &DI = cast<DbgVariableIntrinsic>(I);
     assert(!DI.hasArgList() && "Only dbg.value should currently use DIArgList");
     DILocalVariable *Variable = DI.getVariable();
     DIExpression *Expression = DI.getExpression();
@@ -6149,29 +6151,6 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
 
     bool isParameter = Variable->isParameter() || isa<Argument>(Address);
 
-    // Check if this variable can be described by a frame index, typically
-    // either as a static alloca or a byval parameter.
-    int FI = std::numeric_limits<int>::max();
-    if (const auto *AI =
-            dyn_cast<AllocaInst>(Address->stripInBoundsConstantOffsets())) {
-      if (AI->isStaticAlloca()) {
-        auto I = FuncInfo.StaticAllocaMap.find(AI);
-        if (I != FuncInfo.StaticAllocaMap.end())
-          FI = I->second;
-      }
-    } else if (const auto *Arg = dyn_cast<Argument>(
-                   Address->stripInBoundsConstantOffsets())) {
-      FI = FuncInfo.getArgumentFrameIndex(Arg);
-    }
-
-    // llvm.dbg.declare is handled as a frame index in the MachineFunction
-    // variable table.
-    if (FI != std::numeric_limits<int>::max()) {
-      LLVM_DEBUG(dbgs() << "Skipping " << DI
-                        << " (variable info stashed in MF side table)\n");
-      return;
-    }
-
     SDValue &N = NodeMap[Address];
     if (!N.getNode() && isa<Argument>(Address))
       // Check unused arguments map.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index d4e3f120107ad..36611b117296a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1342,13 +1342,13 @@ static bool isFoldedOrDeadInstruction(const Instruction *I,
          !FuncInfo.isExportedInst(I); // Exported instrs must be computed.
 }
 
-static void processDbgDeclare(FunctionLoweringInfo &FuncInfo,
+static bool processDbgDeclare(FunctionLoweringInfo &FuncInfo,
                               const Value *Address, DIExpression *Expr,
                               DILocalVariable *Var, DebugLoc DbgLoc) {
   if (!Address) {
     LLVM_DEBUG(dbgs() << "processDbgDeclares skipping " << *Var
                       << " (bad address)\n");
-    return;
+    return false;
   }
   MachineFunction *MF = FuncInfo.MF;
   const DataLayout &DL = MF->getDataLayout();
@@ -1373,7 +1373,7 @@ static void processDbgDeclare(FunctionLoweringInfo &FuncInfo,
     FI = FuncInfo.getArgumentFrameIndex(Arg);
 
   if (FI == std::numeric_limits<int>::max())
-    return;
+    return false;
 
   if (Offset.getBoolValue())
     Expr = DIExpression::prepend(Expr, DIExpression::ApplyOffset,
@@ -1383,18 +1383,17 @@ static void processDbgDeclare(FunctionLoweringInfo &FuncInfo,
                     << ", Expr=" << *Expr << ",  FI=" << FI
                     << ", DbgLoc=" << DbgLoc << "\n");
   MF->setVariableDbgInfo(Var, Expr, FI, DbgLoc);
+  return true;
 }
 
 /// Collect llvm.dbg.declare information. This is done after argument lowering
 /// in case the declarations refer to arguments.
 static void processDbgDeclares(FunctionLoweringInfo &FuncInfo) {
-  for (const BasicBlock &BB : *FuncInfo.Fn) {
-    for (const Instruction &I : BB) {
-      if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(&I)) {
-        processDbgDeclare(FuncInfo, DI->getAddress(), DI->getExpression(),
-                          DI->getVariable(), DI->getDebugLoc());
-      }
-    }
+  for (const auto &I : instructions(*FuncInfo.Fn)) {
+    const auto *DI = dyn_cast<DbgDeclareInst>(&I);
+    if (DI && processDbgDeclare(FuncInfo, DI->getAddress(), DI->getExpression(),
+                                DI->getVariable(), DI->getDebugLoc()))
+      FuncInfo.PreprocessedDbgDeclares.insert(DI);
   }
 }