Illegal instruction: 4 when referencing a header file by absolute path

I'm using SourceKitten 0.12.1 from jazzy master with Xcode 7.3.1.

Given the following file /tmp/foo.h:

#import <UIKit/UIKit.h>

@interface UISearchController (Baz)
@property NSString *foo;
@end

When I call sourcekitten with:

sourcekitten doc --objc /tmp/foo.h -- -x objective-c -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.3.sdk --verbose

it crashes with

Apple LLVM version 7.3.0 (clang-703.0.31)
Target: x86_64-apple-darwin15.4.0
Thread model: posix
InstalledDir: 
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.3.sdk/usr/local/include"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.3.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/7.3.0/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.3.sdk/usr/include
 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.3.sdk/System/Library/Frameworks (framework directory)
End of search list.
sourcekit: [1:connection-event-handler:9731: 0.0000] Connection interrupt
sourcekit: [1:pingService:9731: 0.0009] pinging service
Illegal instruction: 4

cd-ing to /tmp and calling it with foo.h as argument doesn't crash (?).

Start by reproducing the sourcekitten doc --objc /tmp/foo.h -- ... command from the report, then compare it with running from /tmp using foo.h. Trace the CLI handling of absolute versus relative header paths; done means both forms process the header without an illegal-instruction crash.