diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -4,10 +4,14 @@
 
 function(get_system_libname libpath libname)
   get_filename_component(libpath ${libpath} NAME)
-  string(REPLACE ";" "|" PREFIXES "${CMAKE_FIND_LIBRARY_PREFIXES}")
-  string(REPLACE ";" "|" SUFFIXES "${CMAKE_FIND_LIBRARY_SUFFIXES}")
-  STRING(REGEX REPLACE "^(${PREFIXES})" "" libpath ${libpath})
-  STRING(REGEX REPLACE "(${SUFFIXES})$" "" libpath ${libpath})
+  if( CMAKE_FIND_LIBRARY_PREFIXES )
+    string(REPLACE ";" "|" PREFIXES "${CMAKE_FIND_LIBRARY_PREFIXES}")
+    string(REGEX REPLACE "^(${PREFIXES})" "" libpath ${libpath})
+  endif()
+  if( CMAKE_FIND_LIBRARY_SUFFIXES )
+    string(REPLACE ";" "|" SUFFIXES "${CMAKE_FIND_LIBRARY_SUFFIXES}")
+    string(REGEX REPLACE "(${SUFFIXES})$" "" libpath ${libpath})
+  endif()
   set(${libname} "${libpath}" PARENT_SCOPE)
 endfunction()