diff --git a/llvm/include/llvm/CodeGen/Passes.h b/llvm/include/llvm/CodeGen/Passes.h
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -578,6 +578,10 @@
   /// otherwise this does nothing
   FunctionPass *createRegAllocScoringPass();
 
+  // Export machine basic block profiles to a file if the necessary command
+  // line flags are set.
+  FunctionPass *createMBBProfileDumpPass();
+
   /// JMC instrument pass.
   ModulePass *createJMCInstrumenterPass();
 
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -337,6 +337,7 @@
 void initializeRegAllocFastPass(PassRegistry&);
 void initializeRegAllocPriorityAdvisorAnalysisPass(PassRegistry &);
 void initializeRegAllocScoringPass(PassRegistry &);
+void initializeMBBProfileDumpPass(PassRegistry &);
 void initializeRegBankSelectPass(PassRegistry&);
 void initializeRegToMemLegacyPass(PassRegistry&);
 void initializeRegUsageInfoCollectorPass(PassRegistry&);
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -144,6 +144,7 @@
   MachineTraceMetrics.cpp
   MachineUniformityAnalysis.cpp
   MachineVerifier.cpp
+  MBBProfileDump.cpp
   MIRFSDiscriminator.cpp
   MIRSampleProfile.cpp
   MIRYamlMapping.cpp
diff --git a/llvm/lib/CodeGen/MBBProfileDump.cpp b/llvm/lib/CodeGen/MBBProfileDump.cpp
new file mode 100644
--- /dev/null
+++ b/llvm/lib/CodeGen/MBBProfileDump.cpp
@@ -0,0 +1,79 @@
+//===- MBBProfileDump.cpp - MBB Profile Dump Pass -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation of the MBB Profile Dump Pass
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+
+static cl::opt<std::string> BasicBlockProfileDump(
+    "mbb-profile-dump", cl::Hidden,
+    cl::desc("Basic block profile dump for external cost modelling. If "
+             "matching up BBs with afterwards, the compilation must be "
+             "performed with -fbasic-block-sections=labels"));
+
+namespace llvm {
+class MBBProfileDump : public MachineFunctionPass {
+public:
+  static char ID;
+  std::unique_ptr<raw_fd_ostream> FileOutput;
+
+  MBBProfileDump() : MachineFunctionPass(ID) {
+    initializeMBBProfileDumpPass(*PassRegistry::getPassRegistry());
+    if (!BasicBlockProfileDump.empty()) {
+      std::error_code PossibleFileError;
+      FileOutput = std::make_unique<raw_fd_ostream>(BasicBlockProfileDump,
+                                                    PossibleFileError);
+    }
+  }
+
+  ~MBBProfileDump() override {
+    if (FileOutput) {
+      FileOutput->close();
+    }
+  }
+
+  StringRef getPassName() const override {
+    return "Register Allocation BB Profile Dump";
+  }
+
+  // Analysis usage
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+    AU.addRequired<MachineBlockFrequencyInfo>();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  // Perform the pass
+  bool runOnMachineFunction(MachineFunction &) override;
+};
+
+char MBBProfileDump::ID = 0;
+FunctionPass *createMBBProfileDumpPass() { return new MBBProfileDump(); }
+
+} // namespace llvm
+
+INITIALIZE_PASS(MBBProfileDump, "mbbprofiledump", "MBB Profile Dump", false,
+                false)
+
+bool MBBProfileDump::runOnMachineFunction(MachineFunction &MF) {
+  if (!BasicBlockProfileDump.empty()) {
+    MachineBlockFrequencyInfo &MBFI = getAnalysis<MachineBlockFrequencyInfo>();
+    for (auto &MBB : MF) {
+      *FileOutput.get() << MF.getName() << "," << MBB.getNumber() << ","
+                        << MBFI.getBlockFreqRelativeToEntryBlock(&MBB) << "\n";
+    }
+  }
+  return false;
+}
diff --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -1273,6 +1273,11 @@
   // Add passes that directly emit MI after all other MI passes.
   addPreEmitPass2();
 
+  // Export machine basic block profile information to be used in downstream
+  // cost modelling applications. This needs to be right before the AsmPrinter
+  // so that nothing following it will mutate MBB numbers or frequencies.
+  addPass(createMBBProfileDumpPass());
+
   AddingMachinePasses = false;
 }
 
diff --git a/llvm/test/CodeGen/MLRegalloc/bb-profile-dump.ll b/llvm/test/CodeGen/MLRegalloc/bb-profile-dump.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/MLRegalloc/bb-profile-dump.ll
@@ -0,0 +1,21 @@
+; REQUIRES: have_tflite
+; REQUIRES: default_triple
+;
+; Check that the basic block profile dump outputs data and in the correct
+; format.
+;
+; RUN: llc -o /dev/null -mbb-profile-dump=%t %s
+; RUN: FileCheck --input-file %t %s
+
+define i64 @f2(i64 %a, i64 %b) {
+    %sum = add i64 %a, %b
+    ret i64 %sum
+}
+
+define i64 @f1() {
+    %sum = call i64 @f2(i64 2, i64 2)
+    ret i64 %sum
+}
+
+; CHECK: f2,0,1.000000e+00
+; CHECK-NEXT: f1,0,1.000000e+00