Index: llvm/lib/ObjCopy/MachO/MachOWriter.cpp
===================================================================
--- llvm/lib/ObjCopy/MachO/MachOWriter.cpp
+++ llvm/lib/ObjCopy/MachO/MachOWriter.cpp
@@ -520,7 +520,8 @@
   uint8_t *CurrHashWritePosition = HashWriteStart;
   while (CurrHashReadPosition < HashReadEnd) {
     StringRef Block(reinterpret_cast<char *>(CurrHashReadPosition),
-                    std::min(HashReadEnd - CurrHashReadPosition,
+                    std::min(static_cast<ssize_t>(HashReadEnd
+                             - CurrHashReadPosition),
                              static_cast<ssize_t>(CodeSignature.BlockSize)));
     SHA256 Hasher;
     Hasher.update(Block);