gistfile1.txt

% ls -l /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs
total 8
drwxrwxr-x 12 root wheel 408 Apr 14 13:36 iPhoneSimulator.sdk
lrwxr-xr-x 1 root wheel 19 Apr 14 13:34 iPhoneSimulator8.3.sdk -> iPhoneSimulator.sdk
% echo "int main() {}" > test.m
% clang -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk -mios-simulator-version-min=7.0 -o test test.m
% clang -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator8.3.sdk -mios-simulator-version-min=7.0 -o test8.3 test.m
% otool -l test | grep -A 3 LC_VERSION_MIN_IPHONEOS
cmd LC_VERSION_MIN_IPHONEOS
cmdsize 16
version 7.0
sdk n/a
% otool -l test8.3 | grep -A 3 LC_VERSION_MIN_IPHONEOS
cmd LC_VERSION_MIN_IPHONEOS
cmdsize 16
version 7.0
sdk 8.3
% sudo ln -s /Applications/Xcode.app /Applications/xcode_6.3.app
% clang -isysroot /Applications/xcode_6.3.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk -mios-simulator-version-min=7.0 -o test_xcode_6.3 test.m
% otool -l test_xcode_6.3 | grep -A 3 LC_VERSION_MIN_IPHONEOS
cmd LC_VERSION_MIN_IPHONEOS
cmdsize 16
version 7.0
sdk 6.3
% clang -isysroot /Applications/xcode_6.3.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator8.3.sdk -mios-simulator-version-min=7.0 -o test_xcode_6.3_sdk_8.3 test.m 
% otool -l test_xcode_6.3_sdk_8.3 | grep -A 3 LC_VERSION_MIN_IPHONEOS
      cmd LC_VERSION_MIN_IPHONEOS
  cmdsize 16
  version 7.0
      sdk 8.3