Why does llvm-config disables exceptions for me?

Question

I was compiling a code using LLVM and it failed compiling:

In file included from main.cpp:8:
In file included from /usr/lib/llvm-12/include/llvm/IR/LLVMContext.h:19:
In file included from /usr/lib/llvm-12/include/llvm/Support/CBindingWrapping.h:17:
/usr/lib/llvm-12/include/llvm/Support/Casting.h:309:7: error: cannot use 'throw' with exceptions disabled
      throw runtime_error("Address sanitizer is not turned on.");
      ^

I realized my llvm-config is disabling the exceptions for me.

llvm-config-12 --cxxflags --ldflags --system-libs --libs core

Returns

-I/usr/lib/llvm-12/include -std=c++14   -fno-exceptions -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
-L/usr/lib/llvm-12/lib 
-lLLVM-12

In the past, I was not observing -fno-exceptions at all. A typical example should look like this.

Where does this exception prevention come from?