Index: clang/include/clang/Basic/CodeGenOptions.def
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.def
+++ clang/include/clang/Basic/CodeGenOptions.def
@@ -325,6 +325,9 @@
 /// emitted.
 VALUE_CODEGENOPT(DwarfVersion, 3, 0)
 
+/// Whether to use experimental new variable location tracking.
+CODEGENOPT(ValueTrackingVariableLocations, 1, 0)
+
 /// Whether we should emit CodeView debug information. It's possible to emit
 /// CodeView and DWARF into the same object.
 CODEGENOPT(EmitCodeView, 1, 0)
Index: clang/include/clang/Driver/CC1Options.td
===================================================================
--- clang/include/clang/Driver/CC1Options.td
+++ clang/include/clang/Driver/CC1Options.td
@@ -389,6 +389,9 @@
     HelpText<"Prints debug information for the new pass manager">;
 def fno_debug_pass_manager : Flag<["-"], "fno-debug-pass-manager">,
     HelpText<"Disables debug printing for the new pass manager">;
+def fexperimental_debug_variable_locations : Flag<["-"],
+    "fexperimental-debug-variable-locations">,
+    HelpText<"Use experimental new value-tracking variable locations">;
 // The driver option takes the key as a parameter to the -msign-return-address=
 // and -mbranch-protection= options, but CC1 has a separate option so we
 // don't have to parse the parameter twice.
Index: clang/lib/CodeGen/BackendUtil.cpp
===================================================================
--- clang/lib/CodeGen/BackendUtil.cpp
+++ clang/lib/CodeGen/BackendUtil.cpp
@@ -516,6 +516,8 @@
   Options.EmitAddrsig = CodeGenOpts.Addrsig;
   Options.ForceDwarfFrameSection = CodeGenOpts.ForceDwarfFrameSection;
   Options.EmitCallSiteInfo = CodeGenOpts.EmitCallSiteInfo;
+  Options.ValueTrackingVariableLocations =
+      CodeGenOpts.ValueTrackingVariableLocations;
   Options.XRayOmitFunctionIndex = CodeGenOpts.XRayOmitFunctionIndex;
 
   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -791,6 +791,9 @@
       llvm::is_contained(DebugEntryValueArchs, T.getArch()))
     Opts.EmitCallSiteInfo = true;
 
+  Opts.ValueTrackingVariableLocations =
+      Args.hasArg(OPT_fexperimental_debug_variable_locations);
+
   Opts.DisableO0ImplyOptNone = Args.hasArg(OPT_disable_O0_optnone);
   Opts.DisableRedZone = Args.hasArg(OPT_disable_red_zone);
   Opts.IndirectTlsSegRefs = Args.hasArg(OPT_mno_tls_direct_seg_refs);
Index: llvm/include/llvm/CodeGen/CommandFlags.h
===================================================================
--- llvm/include/llvm/CodeGen/CommandFlags.h
+++ llvm/include/llvm/CodeGen/CommandFlags.h
@@ -116,6 +116,8 @@
 
 bool getEnableDebugEntryValues();
 
+bool getValueTrackingVariableLocations();
+
 bool getForceDwarfFrameSection();
 
 bool getXRayOmitFunctionIndex();
Index: llvm/include/llvm/Target/TargetOptions.h
===================================================================
--- llvm/include/llvm/Target/TargetOptions.h
+++ llvm/include/llvm/Target/TargetOptions.h
@@ -127,8 +127,8 @@
           EmitStackSizeSection(false), EnableMachineOutliner(false),
           SupportsDefaultOutlining(false), EmitAddrsig(false),
           EmitCallSiteInfo(false), SupportsDebugEntryValues(false),
-          EnableDebugEntryValues(false), ForceDwarfFrameSection(false),
-          XRayOmitFunctionIndex(false),
+          EnableDebugEntryValues(false), ValueTrackingVariableLocations(false),
+          ForceDwarfFrameSection(false), XRayOmitFunctionIndex(false),
           FPDenormalMode(DenormalMode::IEEE, DenormalMode::IEEE) {}
 
     /// PrintMachineCode - This flag is enabled when the -print-machineinstrs
@@ -291,6 +291,11 @@
     /// production.
     bool ShouldEmitDebugEntryValues() const;
 
+    // When set to true, use experimental new debug variable location tracking,
+    // which seeks to follow the values of variables rather than their location,
+    // post isel.
+    unsigned ValueTrackingVariableLocations : 1;
+
     /// Emit DWARF debug frame section.
     unsigned ForceDwarfFrameSection : 1;
 
Index: llvm/lib/CodeGen/CommandFlags.cpp
===================================================================
--- llvm/lib/CodeGen/CommandFlags.cpp
+++ llvm/lib/CodeGen/CommandFlags.cpp
@@ -85,6 +85,7 @@
 CGOPT(bool, EnableAddrsig)
 CGOPT(bool, EmitCallSiteInfo)
 CGOPT(bool, EnableDebugEntryValues)
+CGOPT(bool, ValueTrackingVariableLocations)
 CGOPT(bool, ForceDwarfFrameSection)
 CGOPT(bool, XRayOmitFunctionIndex)
 
@@ -400,6 +401,12 @@
       cl::init(false));
   CGBINDOPT(EnableDebugEntryValues);
 
+  static cl::opt<bool> ValueTrackingVariableLocations(
+      "experimental-debug-variable-locations",
+      cl::desc("Use experimental new value-tracking variable locations"),
+      cl::init(false));
+  CGBINDOPT(ValueTrackingVariableLocations);
+
   static cl::opt<bool> ForceDwarfFrameSection(
       "force-dwarf-frame-section",
       cl::desc("Always emit a debug frame section."), cl::init(false));
@@ -475,6 +482,7 @@
   Options.EmitAddrsig = getEnableAddrsig();
   Options.EmitCallSiteInfo = getEmitCallSiteInfo();
   Options.EnableDebugEntryValues = getEnableDebugEntryValues();
+  Options.ValueTrackingVariableLocations = getValueTrackingVariableLocations();
   Options.ForceDwarfFrameSection = getForceDwarfFrameSection();
   Options.XRayOmitFunctionIndex = getXRayOmitFunctionIndex();
 
Index: llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
===================================================================
--- llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
+++ llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
@@ -13,6 +13,7 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/Passes.h"
+#include "llvm/Target/TargetMachine.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 
@@ -41,7 +42,11 @@
   static char ID;
 
   LiveDebugValues();
-  ~LiveDebugValues() { delete TheImpl; }
+  ~LiveDebugValues()
+  {
+    if (TheImpl)
+      delete TheImpl;
+  }
 
   /// Calculate the liveness information for the given machine function.
   bool runOnMachineFunction(MachineFunction &MF) override;
@@ -58,6 +63,7 @@
 
 private:
   LDVImpl *TheImpl;
+  TargetPassConfig *TPC;
 };
 
 char LiveDebugValues::ID = 0;
@@ -70,10 +76,24 @@
 /// Default construct and initialize the pass.
 LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) {
   initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry());
-  TheImpl = llvm::makeVarLocBasedLiveDebugValues();
+  TheImpl = nullptr;
 }
 
 bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
-  auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
+  if (!TheImpl) {
+    TPC = getAnalysisIfAvailable<TargetPassConfig>();
+
+    bool InstrRefBased = false;
+    if (TPC) {
+      auto &TM = TPC->getTM<TargetMachine>();
+      InstrRefBased = TM.Options.ValueTrackingVariableLocations;
+    }
+
+    if (InstrRefBased)
+      TheImpl = llvm::makeInstrRefBasedLiveDebugValues();
+    else
+      TheImpl = llvm::makeVarLocBasedLiveDebugValues();
+  }
+
   return TheImpl->ExtendRanges(MF, TPC);
 }