Attachment: Download

Issue Description:

I downloaded the prebuilt swift 4.0 and got a seg fault when running the binary executable compiled from bitcode as shown below:

print("Hello World")

$ swiftc hello.swift -emit-bc -o hello.bc

$ clang++ hello.bc -c -o hello.o

$ swiftc hello.o -o hello

$ ./hello

Segmentation fault (core dumped)
(The stack trace is attached)

It works fine if no bitcode file is involved here.

$ swiftc hello.swift -c -o hello.o

$ swiftc hello.o -o hello

$ ./hello

Hello World

I also encountered the same seg fault if I use the prebuilt swift 3.1.1