diff -ur ld64-274.2/src/ld/parsers/lto_file.cpp ld64-274.2+iPhone/src/ld/parsers/lto_file.cpp
--- ld64-274.2/src/ld/parsers/lto_file.cpp	2016-10-21 10:04:17.000000000 -1000
+++ ld64-274.2+iPhone/src/ld/parsers/lto_file.cpp	2018-09-05 11:48:40.000000000 -1000
@@ -291,12 +291,14 @@
 								std::vector<const ld::Atom*>&		newAtoms,
 								std::vector<const char*>&			additionalUndefines);
 
+#if LTO_API_VERSION >= 18
 	static thinlto_code_gen_t init_thinlto_codegen(const std::vector<File*>&           files,
 												   const std::vector<const ld::Atom*>& allAtoms,
 												   ld::Internal&				       state,
 												   const OptimizeOptions&			   options,
 												   CStringToAtom&                      deadllvmAtoms,
 												   CStringToAtom&                      llvmAtoms);
+#endif
 
 	static std::vector<File*>		_s_files;
 	static bool						_s_llvmOptionsProcessed;
@@ -1028,6 +1030,7 @@
 	return true;
 }
 
+#if LTO_API_VERSION >= 18
 // Create the ThinLTO codegenerator
 thinlto_code_gen_t Parser::init_thinlto_codegen(const std::vector<File*>&           files,
 									            const std::vector<const ld::Atom*>& allAtoms,
@@ -1178,6 +1181,7 @@
 
 	return thingenerator;
 }
+#endif
 
 // Full LTO processing
 bool Parser::optimizeThinLTO(const std::vector<File*>&              files,