How To Call @printf in LLVM through the module builder system

    void kprintf(Module *mod, BasicBlock *bb, const char *format, ...)
    {
        Function *func_printf = mod->getFunction("printf");
        if (!func_printf) {
            PointerType *Pty = PointerType::get(IntegerType::get(mod->getContext(), 8), 0);
            FunctionType *FuncTy9 = FunctionType::get(IntegerType::get(mod->getContext(), 32), true);

            func_printf = Function::Create(FuncTy9, GlobalValue::ExternalLinkage, "printf", mod);
            func_printf->setCallingConv(CallingConv::C);

            AttrListPtr func_printf_PAL;
            func_printf->setAttributes(func_printf_PAL);
        }

        IRBuilder <> builder(mod->getContext());
        builder.SetInsertPoint(bb);

        Value *str = builder.CreateGlobalStringPtr(format);
        std::vector <Value *> int32_call_params;
        int32_call_params.push_back(str);

        va_list ap;
        va_start(ap, format);

        char *str_ptr = va_arg(ap, char*);
        Value *format_ptr = builder.CreateGlobalStringPtr(str_ptr);
        int32_call_params.push_back(format_ptr);

        std::vector<llvm::Value*> extra;
        do {
            llvm::Value *op = va_arg(ap, llvm::Value*);
            if (op) {
                int32_call_params.push_back(op);
            } else {
                break;
            }
        } while (1);
        va_end(ap);

        CallInst * int32_call = CallInst::Create(func_printf, int32_call_params, "call", bb);
    }
    #define oprintf(...) kprintf(__VA_ARGS__)
    #define llvm_printf(...) oprintf(mod, bb, __VA_ARGS__, NULL)

    llvm_printf("Output: 0x%08X %f %d\n", 0x12345678, 3.1415926, 12345);

Hope to be of help to you

I found an answer to this problem elsewhere. In fact it goes somewhat beyond my original question but it was helpful for me and hopefully it will help somebody else as well.