What to do when you're not confident your advisor will be able to write you a strong LoR? The title is pretty self-explanatory, but let me explain.

The lab I'm at right now is very big. It's around 30-40 people. I'm a master's student that just finished his first semester and am looking to apply for PhD programs this fall/winter so that if all goes as planned I'll start school in the fall of 2021 right after graduation.

The problem is that my advisor is "more like a business person than an advisor," so to speak. He's always attending networking events, meeting people, etc. rather than advising his own students. The few times that he does hold "meetings" with students is when there's something to be discussed regarding a project that brings in the funding. Even in these meetings it's more like a briefing session where the students fill him in on progress rather than him advising us on what to do.

Anyway, long story short I need him to write me a strong letter but I'm not confident he'll be able to. Your advisor is the one who should be the most familiar with your work, but in all honesty my advisor probably doesn't even know what kind of research at least 90% of his students are doing.

I imagine that it would also look a bit strange on the admissions committees' parts if an applicant's advisor's letter lacks quality content.

What should I do in this situation? I have about 6-7 months until applications open.

Edit

Allure brought up a great point in a comment and I'll try to fill up some more details on how the lab I'm at usually operates.

The lab is usually busy grabbing government or corporate grants (as I assume most are).


The professor pinpoints a few that he wants.
The students write up a proposal and bring it to him, which he assesses. Afterwards he meets with whoever to present the proposals.
If the grant is approved then we get projects to work on.
Teams consisting of PhD students and juniors like myself are assigned to different aspects of the project.
The "meetings" that I mentioned are usually the aforementioned teams briefing the professor, with the PhD students usually doing most of the talking. Honestly speaking, juniors like myself usually just sit there and pretend to take notes.


So yes, usually it's PhD students that I'm working close with, and I'm more than certain that a letter of recommendation from "someone who's not even a PhD" aren't acceptable as LoR's.

My anxiety and worry stems from the fact that, as mentioned above, the most detailed and supportive letter should be from one's advisor. However, I have a strong feeling that it's going to turn up to be a generic one like "student X exhibits very strong research potential!"
The best practical approach is to try to make it as easy as possible for your "hands-off" advisor to write the best letter about you. Even if they delegate the task to someone else, it will be helpful for whoever is writing to have all the relevant information about you. I recommend at least preparing the following: 


A summary of your research accomplishments. If you worked in teams, highlight what you personally added.
A summary of your non-research contributions to the lab. This includes students that you mentored, any responsibilities you took on, other kinds of service to the department or university, and times when you helped others with their research.
A few of your strengths and a specific example for each. 


Whether your recommender uses this information is up to them. Having it  can only increase the odds that their letter is more thorough, specific, and helpful to your application. 

Finally, having an advisor like yours is obviously not ideal, but it is also far from uncommon. I assume that their mentees in the past have gone on to successfully find jobs, postdoctoral appointments, etc. So maybe your advisor cares more about writing recommendations than you might guess based on their advising style. After all, an advisor does have some interest in the success of their students as well.