diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index a027d0c21ba0b..5b233fb365fe2 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -100,6 +100,9 @@ static cl::opt<bool> ExpandConstantExprs(
     cl::desc(
         "Expand constant expressions to instructions for testing purposes"));
 
+// Declare external flag for whether we're using the new debug-info format.
+extern llvm::cl::opt<bool> UseNewDbgInfoFormat;
+
 namespace {
 
 enum {
@@ -6629,6 +6632,9 @@ Error BitcodeReader::materialize(GlobalValue *GV) {
   if (Error Err = materializeMetadata())
     return Err;
 
+  bool NewDebugInfoRequested = F->IsNewDbgInfoFormat;
+  F->IsNewDbgInfoFormat = false;
+
   // Move the bit stream to the saved position of the deferred function body.
   if (Error JumpFailed = Stream.JumpToBit(DFII->second))
     return JumpFailed;
@@ -6704,6 +6710,14 @@ Error BitcodeReader::materialize(GlobalValue *GV) {
   // Look for functions that rely on old function attribute behavior.
   UpgradeFunctionAttributes(*F);
 
+  // If we've materialized a function set up in "new" debug-info mode, the
+  // contents just loaded will still be in dbg.value mode. Switch to the new
+  // mode now. NB: we can add more complicated logic here in the future to
+  // correctly identify when we do and don't need to autoupgrade.
+  if (NewDebugInfoRequested) {
+    F->convertToNewDbgValues();
+  }
+
   // Bring in any functions that this function forward-referenced via
   // blockaddresses.
   return materializeForwardReferencedFunctions();
@@ -8027,6 +8041,15 @@ BitcodeModule::getModuleImpl(LLVMContext &Context, bool MaterializeAll,
     if (Error Err = R->materializeForwardReferencedFunctions())
       return std::move(Err);
   }
+
+  // If we are operating in a "new debug-info" context, upgrade the debug-info
+  // in the loaded module. This is a transitional approach as we enable "new"
+  // debug-info in LLVM, which will eventually be pushed down into the
+  // autoupgrade path once the bitcode-encoding is finalised. Non-materialised
+  // functions will be upgraded in the materialize method.
+  if (UseNewDbgInfoFormat && !M->IsNewDbgInfoFormat)
+    M->convertToNewDbgValues();
+
   return std::move(M);
 }
 
diff --git a/llvm/lib/IR/LegacyPassManager.cpp b/llvm/lib/IR/LegacyPassManager.cpp
index dac4fbce17e40..8945c6dbc8d84 100644
--- a/llvm/lib/IR/LegacyPassManager.cpp
+++ b/llvm/lib/IR/LegacyPassManager.cpp
@@ -530,7 +530,8 @@ bool PassManagerImpl::run(Module &M) {
 
   // RemoveDIs: if a command line flag is given, convert to the DPValue
   // representation of debug-info for the duration of these passes.
-  if (UseNewDbgInfoFormat)
+  bool shouldConvertDbgInfo = UseNewDbgInfoFormat && !M.IsNewDbgInfoFormat;
+  if (shouldConvertDbgInfo)
     M.convertToNewDbgValues();
 
   for (ImmutablePass *ImPass : getImmutablePasses())
@@ -545,7 +546,8 @@ bool PassManagerImpl::run(Module &M) {
   for (ImmutablePass *ImPass : getImmutablePasses())
     Changed |= ImPass->doFinalization(M);
 
-  M.convertFromNewDbgValues();
+  if (shouldConvertDbgInfo)
+    M.convertFromNewDbgValues();
 
   return Changed;
 }
diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
index 1bd562d1e8ae2..8cc0f7fb90991 100644
--- a/llvm/lib/Linker/IRMover.cpp
+++ b/llvm/lib/Linker/IRMover.cpp
@@ -694,6 +694,7 @@ Function *IRLinker::copyFunctionProto(const Function *SF) {
                              SF->getAddressSpace(), SF->getName(), &DstM);
   F->copyAttributesFrom(SF);
   F->setAttributes(mapAttributeTypes(F->getContext(), F->getAttributes()));
+  F->IsNewDbgInfoFormat = SF->IsNewDbgInfoFormat;
   return F;
 }
 
diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 71d0f09e47713..b4c28035cdbf1 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -1048,9 +1048,13 @@ void Mapper::remapFunction(Function &F) {
       A.mutateType(TypeMapper->remapType(A.getType()));
 
   // Remap the instructions.
-  for (BasicBlock &BB : F)
-    for (Instruction &I : BB)
+  for (BasicBlock &BB : F) {
+    for (Instruction &I : BB) {
       remapInstruction(&I);
+      for (DPValue &DPV : I.DbgMarker->getDbgValueRange())
+        remapDPValue(DPV);
+    }
+  }
 }
 
 void Mapper::mapAppendingVariable(GlobalVariable &GV, Constant *InitPrefix,
diff --git a/llvm/test/LTO/X86/pr38046.ll b/llvm/test/LTO/X86/pr38046.ll
index 8f04190f0c83f..ddcc0f42cf231 100644
--- a/llvm/test/LTO/X86/pr38046.ll
+++ b/llvm/test/LTO/X86/pr38046.ll
@@ -5,6 +5,14 @@
 ; RUN: llvm-dis %t.lto.o.0.2.internalize.bc >/dev/null 2>%t.dis.stderr || true
 ; RUN: FileCheck -allow-empty %s < %t.dis.stderr
 
+;; Re-run with "new" debug-info mode to ensure the variable location information
+;; is handled gracefully.
+; RUN: llvm-lto2 run -save-temps -o %t.lto.o %t.o \
+; RUN:   -r=%t.o,foo,plx \
+; RUN:   -r=%t.o,get,pl --try-experimental-debuginfo-iterators
+; RUN: llvm-dis %t.lto.o.0.2.internalize.bc >/dev/null 2>%t.dis.stderr || true
+; RUN: FileCheck -allow-empty %s < %t.dis.stderr
+
 ; CHECK-NOT: Global is external, but doesn't have external or weak linkage
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/Linker/debug-info-use-before-def.ll b/llvm/test/Linker/debug-info-use-before-def.ll
index ac5f3148f83c7..d32dd97f4ffaf 100644
--- a/llvm/test/Linker/debug-info-use-before-def.ll
+++ b/llvm/test/Linker/debug-info-use-before-def.ll
@@ -1,4 +1,5 @@
 ; RUN: llvm-link -S %s | FileCheck %s
+; RUN: llvm-link -S %s --try-experimental-debuginfo-iterators | FileCheck %s
 
 ; Test that when a debug metadata use-before-def is run through llvm-link, the
 ; value reference is preserved. Tests both singular uses and DIArgList uses of
diff --git a/llvm/test/Linker/thinlto_funcimport_debug.ll b/llvm/test/Linker/thinlto_funcimport_debug.ll
index 294b3a773ef51..5a69fc6492b24 100644
--- a/llvm/test/Linker/thinlto_funcimport_debug.ll
+++ b/llvm/test/Linker/thinlto_funcimport_debug.ll
@@ -6,6 +6,10 @@
 ; If we import func1 and not func2 we should only link DISubprogram for func1
 ; RUN: llvm-link %t2.bc -summary-index=%t3.thinlto.bc -import=func1:%t.bc -S | FileCheck %s
 
+;; Repeat runlines using "new" debuginfo iterators mode.
+; RUN: llvm-lto -thinlto -o %t3 %t.bc %t2.bc --try-experimental-debuginfo-iterators
+; RUN: llvm-link %t2.bc -summary-index=%t3.thinlto.bc -import=func1:%t.bc -S --try-experimental-debuginfo-iterators | FileCheck %s
+
 ; CHECK: declare i32 @func2
 ; CHECK: define available_externally i32 @func1
 
diff --git a/llvm/test/ThinLTO/X86/debuginfo-cu-import.ll b/llvm/test/ThinLTO/X86/debuginfo-cu-import.ll
index 850ef09b1c2f0..56269f8f84854 100644
--- a/llvm/test/ThinLTO/X86/debuginfo-cu-import.ll
+++ b/llvm/test/ThinLTO/X86/debuginfo-cu-import.ll
@@ -13,6 +13,10 @@
 ; CHECK-NOT: DICompileUnit{{.*}} globals:
 ; CHECK-NOT: DICompileUnit{{.*}} imports:
 
+;; Repeat test in RemoveDIs debug-info mode to check that bitcode is loaded and
+;; converted correctly.
+; RUN: llvm-lto -thinlto-action=import %t2.bc -thinlto-index=%t.index.bc -o - --try-experimental-debuginfo-iterators | llvm-dis -o - | FileCheck %s
+
 ; ModuleID = 'debuginfo-cu-import.c'
 source_filename = "debuginfo-cu-import.c"
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/ThinLTO/X86/pr35472.ll b/llvm/test/ThinLTO/X86/pr35472.ll
index f7b19e8ba7969..f214c607f3d28 100644
--- a/llvm/test/ThinLTO/X86/pr35472.ll
+++ b/llvm/test/ThinLTO/X86/pr35472.ll
@@ -9,6 +9,12 @@
 ; RUN: llvm-nm %t1.bc.thinlto.o | FileCheck %s -check-prefix=ThinLTOa
 ; RUN: llvm-nm %t2.bc.thinlto.o | FileCheck %s -check-prefix=ThinLTOb
 
+;; Re-run with "new" debug-info mode, checking that we load / convert / emit
+;; the dbg.declares below correctly.
+; RUN: llvm-lto -thinlto-action=run %t1.bc %t2.bc -exported-symbol=_Z5Alphav --try-experimental-debuginfo-iterators
+; RUN: llvm-nm %t1.bc.thinlto.o | FileCheck %s -check-prefix=ThinLTOa
+; RUN: llvm-nm %t2.bc.thinlto.o | FileCheck %s -check-prefix=ThinLTOb
+
 ; ThinLTOa-DAG: T _Z5Bravov
 ; ThinLTOa-DAG: W _ZN4EchoD2Ev
 ; ThinLTOb-DAG: T _Z5Alphav
diff --git a/llvm/tools/llvm-link/llvm-link.cpp b/llvm/tools/llvm-link/llvm-link.cpp
index a476b50a1ed90..d50e0678f4610 100644
--- a/llvm/tools/llvm-link/llvm-link.cpp
+++ b/llvm/tools/llvm-link/llvm-link.cpp
@@ -129,6 +129,13 @@ static cl::opt<bool> IgnoreNonBitcode(
     cl::desc("Do not report an error for non-bitcode files in archives"),
     cl::Hidden);
 
+static cl::opt<bool> TryUseNewDbgInfoFormat(
+    "try-experimental-debuginfo-iterators",
+    cl::desc("Enable debuginfo iterator positions, if they're built in"),
+    cl::init(false));
+
+extern cl::opt<bool> UseNewDbgInfoFormat;
+
 static ExitOnError ExitOnErr;
 
 // Read the specified bitcode file in and return it. This routine searches the
@@ -465,6 +472,17 @@ int main(int argc, char **argv) {
   cl::HideUnrelatedOptions({&LinkCategory, &getColorCategory()});
   cl::ParseCommandLineOptions(argc, argv, "llvm linker\n");
 
+  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
+  // new debug-info format, if it's built in.
+#ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
+  if (TryUseNewDbgInfoFormat) {
+    // If LLVM was built with support for this, turn the new debug-info format
+    // on.
+    UseNewDbgInfoFormat = true;
+  }
+#endif
+  (void)TryUseNewDbgInfoFormat;
+
   LLVMContext Context;
   Context.setDiagnosticHandler(std::make_unique<LLVMLinkDiagnosticHandler>(),
                                true);
diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
index 735b3763f5b2f..f27281438282b 100644
--- a/llvm/tools/llvm-lto/llvm-lto.cpp
+++ b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -264,6 +264,13 @@ static cl::opt<bool>
     LTOSaveBeforeOpt("lto-save-before-opt", cl::init(false),
                      cl::desc("Save the IR before running optimizations"));
 
+static cl::opt<bool> TryUseNewDbgInfoFormat(
+    "try-experimental-debuginfo-iterators",
+    cl::desc("Enable debuginfo iterator positions, if they're built in"),
+    cl::init(false), cl::Hidden);
+
+extern cl::opt<bool> UseNewDbgInfoFormat;
+
 namespace {
 
 struct ModuleInfo {
@@ -937,6 +944,17 @@ int main(int argc, char **argv) {
   cl::HideUnrelatedOptions({&LTOCategory, &getColorCategory()});
   cl::ParseCommandLineOptions(argc, argv, "llvm LTO linker\n");
 
+  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
+  // new debug-info format, if it's built in.
+#ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
+  if (TryUseNewDbgInfoFormat) {
+    // If LLVM was built with support for this, turn the new debug-info format
+    // on.
+    UseNewDbgInfoFormat = true;
+  }
+#endif
+  (void)TryUseNewDbgInfoFormat;
+
   if (OptLevel < '0' || OptLevel > '3')
     error("optimization level must be between 0 and 3");
 
diff --git a/llvm/tools/llvm-lto2/llvm-lto2.cpp b/llvm/tools/llvm-lto2/llvm-lto2.cpp
index 81c97a994038d..c212374a0eccb 100644
--- a/llvm/tools/llvm-lto2/llvm-lto2.cpp
+++ b/llvm/tools/llvm-lto2/llvm-lto2.cpp
@@ -187,6 +187,13 @@ static cl::opt<bool> EnableFreestanding(
     cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"),
     cl::Hidden);
 
+static cl::opt<bool> TryUseNewDbgInfoFormat(
+    "try-experimental-debuginfo-iterators",
+    cl::desc("Enable debuginfo iterator positions, if they're built in"),
+    cl::init(false), cl::Hidden);
+
+extern cl::opt<bool> UseNewDbgInfoFormat;
+
 static void check(Error E, std::string Msg) {
   if (!E)
     return;
@@ -222,6 +229,17 @@ static int usage() {
 static int run(int argc, char **argv) {
   cl::ParseCommandLineOptions(argc, argv, "Resolution-based LTO test harness");
 
+  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
+  // new debug-info format, if it's built in.
+#ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
+  if (TryUseNewDbgInfoFormat) {
+    // If LLVM was built with support for this, turn the new debug-info format
+    // on.
+    UseNewDbgInfoFormat = true;
+  }
+#endif
+  (void)TryUseNewDbgInfoFormat;
+
   // FIXME: Workaround PR30396 which means that a symbol can appear
   // more than once if it is defined in module-level assembly and
   // has a GV declaration. We allow (file, symbol) pairs to have multiple