diff --git a/include/clang-c/CXCppInterOp.h b/include/clang-c/CXCppInterOp.h
index c1231dfbc..a775cd41d 100644
--- a/include/clang-c/CXCppInterOp.h
+++ b/include/clang-c/CXCppInterOp.h
@@ -56,6 +56,11 @@ TInterp_t clang_interpreter_getInterpreterAsPtr(CXInterpreter I);
  */
 TInterp_t clang_interpreter_takeInterpreterAsPtr(CXInterpreter I);
 
+/**
+ * Undo N previous incremental inputs.
+ */
+CXErrorCode clang_interpreter_Undo(CXInterpreter I, unsigned int N);
+
 /**
  * Dispose of the given interpreter context.
  */
@@ -144,7 +149,7 @@ typedef void* CXValue;
  *
  * \returns a \c CXValue.
  */
-CXValue clang_createValue();
+CXValue clang_createValue(void);
 
 /**
  * Dispose of the given CXValue.
diff --git a/lib/Interpreter/CXCppInterOp.cpp b/lib/Interpreter/CXCppInterOp.cpp
index 28a91c667..4868f7581 100644
--- a/lib/Interpreter/CXCppInterOp.cpp
+++ b/lib/Interpreter/CXCppInterOp.cpp
@@ -70,6 +70,10 @@ TInterp_t clang_interpreter_takeInterpreterAsPtr(CXInterpreter I) {
   return static_cast<CXInterpreterImpl*>(I)->Interp.release();
 }
 
+CXErrorCode clang_interpreter_Undo(CXInterpreter I, unsigned int N) {
+  return getInterpreter(I)->Undo(N) ? CXError_Failure : CXError_Success;
+}
+
 void clang_interpreter_dispose(CXInterpreter I) {
   delete I; // NOLINT(*-owning-memory)
 }
@@ -113,7 +117,7 @@ enum CXErrorCode clang_interpreter_process(CXInterpreter I, const char* code) {
   return CXError_Success;
 }
 
-CXValue clang_createValue() {
+CXValue clang_createValue(void) {
 #ifdef USE_CLING
   auto val = std::make_unique<cling::Value>();
 #else