PySide2 with Qt 5.9 fails to build with pyside-setup.py due to error: definition of builtin function

When trying to build PySide 5.9 using the pyside-setup 5.9 head (commit 9d454fbb9808a337dbcc4c9703c1359c8698fff0), the build fails right after the message "Running generator for QtCore...".

The precise error is as follows:
clang_parseTranslationUnit2(0x0, cmd[16]=-nostdinc -isystem/usr/include/c+/5 -isystem/usr/include/x86_64-linux-gnu/c/5 -isystem/usr/include/c/5/backward -isystem/usr/lib/gcc/x86_64-linux-gnu/5/include -isystem/usr/local/include -isystem/usr/lib/gcc/x86_64-linux-gnu/5/include-fixed -isystem/usr/include/x86_64-linux-gnu -isystem/usr/include -std=c+14 -fPIC -fno-exceptions -Wno-constant-logical-operand -I/home/close/Project/projectclient/pyside/pyside-setup/sources/pyside2/PySide2 -I/home/close/Qt/5.9/gcc_64/include/ /tmp/pyside2_global_J10965.hpp)
/usr/lib/gcc/x86_64-linux-gnu/5/include/ia32intrin.h:104:1: error: definition of builtin function '__rdtsc'
/usr/lib/gcc/x86_64-linux-gnu/5/include/xmmintrin.h:818:1: error: definition of builtin function '_mm_getcsr'
/usr/lib/gcc/x86_64-linux-gnu/5/include/xmmintrin.h:850:1: error: definition of builtin function '_mm_setcsr'
[...] more builtin function errors.

The command includes -isystem/usr/lib/gcc/x86_64-linux-gnu/5/include -isystem/usr/local/include -isystem/usr/lib/gcc/x86_64-linux-gnu/5/include-fixed

However, these functions are already defined elsewhere, see https://www.mail-archive.com/llvm-bugs@lists.llvm.org/msg12168.html