How to reimplement AsmPrinter in LLVM-Clang to generate my own directive set?

Question

I'm using LLVM and Clang to generate assembly listing from .c file. Instructions are printed correctly, but in the beginning and in the end LLVM-Clang inserts default directives incompatible with my architecture. I overrode AsmPrinter class to get own directives, but I succeeded only in adding new directives not in replacing them. For instance:

MyAsmPrinter.c:

class MyAsmPrinter : public AsmPrinter { 
...
    void EmitStartOfAsmFile(Module &M) override;
    void EmitEndOfAsmFile(Module &M) override;
...
}

void MyAsmPrinter::EmitStartOfAsmFile(Module &M) {
    <--- insert something (A)
}

void MyAsmPrinter::EmitEndOfAsmFile(Module &M) {
    <--- insert something (B)
}

clangtest.c:

int main() 
{
  int a, b;
  b = 3;
  a = b*b;
  return a;
}

I type:

./bin/clang -target mytarget -S clangtest.c -o test.s

And get

.text
<--- (A goes here)
.file   "clangtest.c"
.globl  main
.type   main,@function
    main:
    (correct asm code here)
.Ltmp0:
    .size   main, .Ltmp0-main


.ident  "clang version 3.6.0 ..."
.section    ".note.GNU-stack","",@progbits
<--- (B goes here)

But I want to get rid of ".text", ".file" and ".ident" at all. Where they get inserted anyway? I tried googling it, greping source code for other targets and LLVM source code, but found nothing. So, could anyone give me a hint how to do this?