diff --git a/llvm/include/llvm/Transforms/Utils/CodeExtractor.h b/llvm/include/llvm/Transforms/Utils/CodeExtractor.h
--- a/llvm/include/llvm/Transforms/Utils/CodeExtractor.h
+++ b/llvm/include/llvm/Transforms/Utils/CodeExtractor.h
@@ -139,6 +139,20 @@
     /// returns false.
     Function *extractCodeRegion(const CodeExtractorAnalysisCache &CEAC);
 
+    /// Perform the extraction, returning the new function and providing an
+    /// interface to see what was categorized as inputs and outputs.
+    ///
+    /// \param CEAC - Cache to speed up operations for the CodeExtractor when
+    /// hoisting, and extracting lifetime values and assumes.
+    /// \param Inputs [out] - filled with  values marked as inputs to the
+    /// newly outlined function.
+     /// \param Outputs [out] - filled with values marked as outputs to the
+    /// newly outlined function.
+    /// \returns zero when called on a CodeExtractor instance where isEligible
+    /// returns false.
+    Function *extractCodeRegion(const CodeExtractorAnalysisCache &CEAC,
+                                ValueSet &Inputs, ValueSet &Outputs);
+
     /// Verify that assumption cache isn't stale after a region is extracted.
     /// Returns true when verifier finds errors. AssumptionCache is passed as
     /// parameter to make this function stateless.
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -1575,6 +1575,13 @@
 
 Function *
 CodeExtractor::extractCodeRegion(const CodeExtractorAnalysisCache &CEAC) {
+  ValueSet Inputs, Outputs;
+  return extractCodeRegion(CEAC, Inputs, Outputs);
+}
+
+Function *
+CodeExtractor::extractCodeRegion(const CodeExtractorAnalysisCache &CEAC,
+                                 ValueSet &inputs, ValueSet &outputs) {
   if (!isEligible())
     return nullptr;
 
@@ -1663,7 +1670,7 @@
   }
   newFuncRoot->getInstList().push_back(BranchI);
 
-  ValueSet inputs, outputs, SinkingCands, HoistingCands;
+  ValueSet SinkingCands, HoistingCands;
   BasicBlock *CommonExit = nullptr;
   findAllocas(CEAC, SinkingCands, HoistingCands, CommonExit);
   assert(HoistingCands.empty() || CommonExit);
diff --git a/llvm/unittests/Transforms/Utils/CodeExtractorTest.cpp b/llvm/unittests/Transforms/Utils/CodeExtractorTest.cpp
--- a/llvm/unittests/Transforms/Utils/CodeExtractorTest.cpp
+++ b/llvm/unittests/Transforms/Utils/CodeExtractorTest.cpp
@@ -77,6 +77,64 @@
   EXPECT_FALSE(verifyFunction(*Func));
 }
 
+TEST(CodeExtractor, InputOutputMonitoring) {
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
+    define i32 @foo(i32 %x, i32 %y, i32 %z) {
+    header:
+      %0 = icmp ugt i32 %x, %y
+      br i1 %0, label %body1, label %body2
+
+    body1:
+      %1 = add i32 %z, 2
+      br label %notExtracted
+
+    body2:
+      %2 = mul i32 %z, 7
+      br label %notExtracted
+
+    notExtracted:
+      %3 = phi i32 [ %1, %body1 ], [ %2, %body2 ]
+      %4 = add i32 %3, %x
+      ret i32 %4
+    }
+  )invalid",
+                                                Err, Ctx));
+
+  Function *Func = M->getFunction("foo");
+  SmallVector<BasicBlock *, 3> Candidates{getBlockByName(Func, "header"),
+                                          getBlockByName(Func, "body1"),
+                                          getBlockByName(Func, "body2")};
+
+  CodeExtractor CE(Candidates);
+  EXPECT_TRUE(CE.isEligible());
+
+  CodeExtractorAnalysisCache CEAC(*Func);
+  SetVector<Value *> Inputs, Outputs;
+  Function *Outlined = CE.extractCodeRegion(CEAC, Inputs, Outputs);
+  EXPECT_TRUE(Outlined);
+
+  EXPECT_EQ(Inputs.size(), 3u);
+  EXPECT_EQ(Inputs[0], Func->getArg(2));
+  EXPECT_EQ(Inputs[1], Func->getArg(0));
+  EXPECT_EQ(Inputs[2], Func->getArg(1));
+  EXPECT_EQ(Outputs.size(), 1u);
+  StoreInst *SI = cast<StoreInst>(Outlined->getArg(3)->user_back());
+  Value *OutputVal = SI->getValueOperand();
+  EXPECT_EQ(Outputs[0], OutputVal);
+  BasicBlock *Exit = getBlockByName(Func, "notExtracted");
+  BasicBlock *ExitSplit = getBlockByName(Outlined, "notExtracted.split");
+  // Ensure that PHI in exit block has only one incoming value (from code
+  // replacer block).
+  EXPECT_TRUE(Exit && cast<PHINode>(Exit->front()).getNumIncomingValues() == 1);
+  // Ensure that there is a PHI in outlined function with 2 incoming values.
+  EXPECT_TRUE(ExitSplit &&
+              cast<PHINode>(ExitSplit->front()).getNumIncomingValues() == 2);
+  EXPECT_FALSE(verifyFunction(*Outlined));
+  EXPECT_FALSE(verifyFunction(*Func));
+}
+
 TEST(CodeExtractor, ExitPHIOnePredFromRegion) {
   LLVMContext Ctx;
   SMDiagnostic Err;