diff --git a/llvm/lib/CodeGen/RemoveRedundantDebugValues.cpp b/llvm/lib/CodeGen/RemoveRedundantDebugValues.cpp
--- a/llvm/lib/CodeGen/RemoveRedundantDebugValues.cpp
+++ b/llvm/lib/CodeGen/RemoveRedundantDebugValues.cpp
@@ -12,6 +12,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/Register.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/Function.h"
@@ -30,6 +31,8 @@
 
 STATISTIC(NumRemovedBackward, "Number of DBG_VALUEs removed (backward scan)");
 STATISTIC(NumRemovedForward, "Number of DBG_VALUEs removed (forward scan)");
+STATISTIC(PeakVariableMapSize, "Maximum size of VariableMap (forward scan)");
+STATISTIC(PeakRegisterSetSize, "Maximum size of RegisterSet (forward scan)");
 
 namespace {
 
@@ -87,6 +90,11 @@
       VariableMap;
   const auto *TRI = MBB.getParent()->getSubtarget().getRegisterInfo();
 
+  // Checking if an MI modifies a register is not trivial, so instead of
+  // directly checking the register of everything in VariableMap, we collect all
+  // the registers here and only check this set. If any register is clobbered,
+  // we can do a trivial register comparison to remove it from VariableMap.
+  DenseSet<Register> RegisterSet;
   for (auto &MI : MBB) {
     if (MI.isDebugValue()) {
       DebugVariable Var(MI.getDebugVariable(), std::nullopt,
@@ -116,6 +124,10 @@
           VMI->second.first->getReg() != Loc.getReg() ||
           VMI->second.second != MI.getDebugExpression()) {
         VariableMap[Var] = {&Loc, MI.getDebugExpression()};
+        PeakVariableMapSize.updateMax(VariableMap.size());
+
+        RegisterSet.insert(Loc.getReg());
+        PeakRegisterSetSize.updateMax(RegisterSet.size());
         continue;
       }
 
@@ -128,10 +140,15 @@
       continue;
 
     // Stop tracking any location that is clobbered by this instruction.
-    for (auto &Var : VariableMap) {
-      auto &LocOp = Var.second.first;
-      if (MI.modifiesRegister(LocOp->getReg(), TRI))
-        VariableMap.erase(Var.first);
+    for (const Register reg : RegisterSet) {
+      if (MI.modifiesRegister(reg, TRI)) {
+        for (auto &Var : VariableMap) {
+          const auto &LocOp = Var.second.first;
+          if (LocOp->getReg() == reg)
+            VariableMap.erase(Var.first);
+        }
+        RegisterSet.erase(reg);
+      }
     }
   }