diff --git a/lib/AsmParser/CMakeLists.txt b/lib/AsmParser/CMakeLists.txt
index b8283c5d8a7..62e6dce796d 100644
--- a/lib/AsmParser/CMakeLists.txt
+++ b/lib/AsmParser/CMakeLists.txt
@@ -2,34 +2,27 @@
 include(FindBison)
 find_bison()
 
-IF(BISON_EXECUTABLE)
-bison_generator(
-  "llvmAsm"
-  "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.y"
-  "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h"
-  "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp"
-  )
-ELSE(BISON_EXECUTABLE)
-  MESSAGE(STATUS "Bison not found, the pregenerated files will be used")
-
-  IF(WIN32)
-    FILE(TO_NATIVE_PATH ${CMAKE_CURRENT_SOURCE_DIR} WIN_SOURCE_DIR)
-
-    ADD_CUSTOM_COMMAND(
-      OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp"
-      DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp.cvs"
-      COMMAND copy \"${WIN_SOURCE_DIR}\\llvmAsmParser.cpp.cvs\" \"${WIN_SOURCE_DIR}\\llvmAsmParser.cpp\"
+if(BISON_EXECUTABLE)
+  bison_generator(
+    "llvmAsm"
+    "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.y"
+    "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h"
+    "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp"
     )
-    ADD_CUSTOM_COMMAND(
-      OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h"
-      DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h.cvs"
-      COMMAND copy \"${WIN_SOURCE_DIR}\\llvmAsmParser.h.cvs\" \"${WIN_SOURCE_DIR}\\llvmAsmParser.h\"
+else(BISON_EXECUTABLE)
+  message(STATUS "Bison not found, the pregenerated files will be used")
+
+  add_custom_command(
+    OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp"
+    DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp.cvs"
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp.cvs" "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.cpp"
     )
-  ELSE(WIN32)
-    MESSAGE(SEND_ERROR "Not implemented")
-    # fixme do the same with cp instead of copy
-  ENDIF(WIN32)
-ENDIF(BISON_EXECUTABLE)
+  add_custom_command(
+    OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h"
+    DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h.cvs"
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h.cvs" "${CMAKE_CURRENT_SOURCE_DIR}/llvmAsmParser.h"
+    )
+endif(BISON_EXECUTABLE)
 
 add_llvm_library(LLVMAsmParser
   llvmAsmParser.cpp  # Generated from llvmAsmParser.y or copyied from corresponding .cvs