Index: cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- cmake/modules/HandleLLVMOptions.cmake
+++ cmake/modules/HandleLLVMOptions.cmake
@@ -222,6 +222,12 @@
   endif( LLVM_BUILD_32_BITS )
 endif( CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32 )
 
+# If building on a 32-bit system, make sure off_t can store offsets > 2GB
+if( CMAKE_SIZEOF_VOID_P EQUAL 4 )
+  add_definitions( -D_LARGEFILE_SOURCE )
+  add_definitions( -D_FILE_OFFSET_BITS=64 )
+endif()
+
 if( XCODE )
   # For Xcode enable several build settings that correspond to
   # many warnings that are on by default in Clang but are