diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.hindex c35311c886413..b929585205aee 100644--- a/clang/include/clang-c/Index.h+++ b/clang/include/clang-c/Index.h@@ -6953,6 +6953,21 @@ clang_getCursorUnaryOperatorKind(CXCursor cursor);  * @}  */+CINDEX_DEPRECATED+typedef void *CXRemapping;++CINDEX_DEPRECATED CINDEX_LINKAGE CXRemapping clang_getRemappings(const char *);++CINDEX_DEPRECATED CINDEX_LINKAGE CXRemapping+clang_getRemappingsFromFileList(const char **, unsigned);++CINDEX_DEPRECATED CINDEX_LINKAGE unsigned clang_remap_getNumFiles(CXRemapping);++CINDEX_DEPRECATED CINDEX_LINKAGE void+clang_remap_getFilenames(CXRemapping, unsigned, CXString *, CXString *);++CINDEX_DEPRECATED CINDEX_LINKAGE void clang_remap_dispose(CXRemapping);+ LLVM_CLANG_C_EXTERN_C_END  #endifdiff --git a/clang/tools/libclang/CMakeLists.txt b/clang/tools/libclang/CMakeLists.txtindex b6662b66206b2..2b1e266f07392 100644--- a/clang/tools/libclang/CMakeLists.txt+++ b/clang/tools/libclang/CMakeLists.txt@@ -42,6 +42,7 @@ set(SOURCES   Indexing.cpp   FatalErrorHandler.cpp   Rewrite.cpp+  Obsolete.cpp    ADDITIONAL_HEADERS   CIndexDiagnostic.hdiff --git a/clang/tools/libclang/Obsolete.cpp b/clang/tools/libclang/Obsolete.cppnew file mode 100644index 0000000000000..3596f76e1be6f--- /dev/null+++ b/clang/tools/libclang/Obsolete.cpp@@ -0,0 +1,48 @@+//===- Obsolete.cpp - Obsolete libclang functions and types -------------===//+//+// 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+//+//===--------------------------------------------------------------------===//+//+// This file contains libclang symbols whose underlying functionality has been+// removed from Clang, but which need to be kept around so as to retain ABI+// compatibility.+//+//===--------------------------------------------------------------------===//++#include "clang-c/CXString.h"+#include "clang-c/Index.h"+#include "clang-c/Platform.h"+#include "llvm/Support/raw_ostream.h"++extern "C" {++// The functions below used to be part of the C API for ARCMigrate, which has+// since been removed from Clang; they already used to print an error if Clang+// was compiled without arcmt support, so we continue doing so.+CXRemapping clang_getRemappings(const char *) {+  llvm::errs() << "error: ARCMigrate has been removed from Clang";+  return nullptr;+}++CXRemapping clang_getRemappingsFromFileList(const char **, unsigned) {+  llvm::errs() << "error: ARCMigrate has been removed from Clang";+  return nullptr;+}++unsigned clang_remap_getNumFiles(CXRemapping) {+  llvm::errs() << "error: ARCMigrate has been removed from Clang";+  return 0;+}++void clang_remap_getFilenames(CXRemapping, unsigned, CXString *, CXString *) {+  llvm::errs() << "error: ARCMigrate has been removed from Clang";+}++void clang_remap_dispose(CXRemapping) {+  llvm::errs() << "error: ARCMigrate has been removed from Clang";+}++} // extern "C"diff --git a/llvm/utils/gn/secondary/clang/tools/libclang/BUILD.gn b/llvm/utils/gn/secondary/clang/tools/libclang/BUILD.gnindex 8f7beea152ab7..30b8bb61184bd 100644--- a/llvm/utils/gn/secondary/clang/tools/libclang/BUILD.gn+++ b/llvm/utils/gn/secondary/clang/tools/libclang/BUILD.gn@@ -87,6 +87,7 @@ shared_library("libclang") {     "Index_Internal.h",     "Indexing.cpp",     "Rewrite.cpp",+    "Obsolete.cpp",   ]   if (host_os == "mac") {     ldflags = [