As our reliance on computers increases, so does the need for robust software. Previous studies have shown that many C libraries exhibit robustness problems due to exceptional inputs. This paper describes the HEALERS system that uses an automated approach to increasing the robustness of C libraries without source code access. The system extracts the C type information for a shared library using header files and manual pages. Then it generates for each global function a fault-injector to determine a "robust" argument type for each argument. Based on this information and optionally, some manual editing, the system generates a robustness wrapper that performs careful argument checking before invoking C library functions. A robustness evaluation using Ballista tests has shown that our wrapper can prevent crash, hang, and abort failures. Moreover, the wrapper generation process is highly automated and can easily adapt to new library releases.