diff --git a/llvm/include/llvm-c/lto.h b/llvm/include/llvm-c/lto.h
--- a/llvm/include/llvm-c/lto.h
+++ b/llvm/include/llvm-c/lto.h
@@ -44,7 +44,7 @@
  * @{
  */
 
-#define LTO_API_VERSION 24
+#define LTO_API_VERSION 25
 
 /**
  * \since prior to LTO_API_VERSION=3
@@ -793,6 +793,23 @@
                                                     size_t index,
                                                     size_t *size);
 
+/**
+ * Returns the number of libcall symbols that can be generated by LTO
+ * code generator that might not be visile from the symbol table of
+ * bitcode files.
+ *
+ * \since prior to LTO_API_VERSION=25
+ */
+extern unsigned int
+lto_get_num_runtime_lib_symbols();
+
+/**
+ * Returns the name of the ith symbol in the list of possible libcall symbols.
+ *
+ * \since prior to LTO_API_VERSION=25
+ */
+extern const char*
+lto_get_runtime_lib_symbol_name(unsigned int index);
 
 /**
  * @} // endgoup LLVMCTLTO
diff --git a/llvm/tools/lto/lto.cpp b/llvm/tools/lto/lto.cpp
--- a/llvm/tools/lto/lto.cpp
+++ b/llvm/tools/lto/lto.cpp
@@ -652,3 +652,18 @@
                                                    size_t *size) {
   return LTOModule::getDependentLibrary(unwrap(input), index, size);
 }
+
+static const char *libcallRoutineNames[] = {
+#define HANDLE_LIBCALL(code, name) name,
+#include "llvm/IR/RuntimeLibcalls.def"
+#undef HANDLE_LIBCALL
+};
+
+unsigned int lto_get_num_runtime_lib_symbols() {
+  return makeArrayRef(libcallRoutineNames).size();
+}
+
+const char*
+lto_get_runtime_lib_symbol_name(unsigned int index) {
+  return makeArrayRef(libcallRoutineNames)[index];
+}
diff --git a/llvm/tools/lto/lto.exports b/llvm/tools/lto/lto.exports
--- a/llvm/tools/lto/lto.exports
+++ b/llvm/tools/lto/lto.exports
@@ -76,3 +76,5 @@
 lto_input_dispose
 lto_input_get_num_dependent_libraries
 lto_input_get_dependent_library
+lto_get_num_runtime_lib_symbols
+lto_get_runtime_lib_symbol_name