Update README.md

Author: amzamora

README.md

@@ -1,2 +1,47 @@
 # LLVM binaries
-Prebuilt versions of LLVM and LLD for plataforms that diamond supports.
+Prebuilt versions of LLVM and LLD for diamond.
+
+## Requirements
+- A C++ compiler
+- Ninja
+- LLD
+
+## Steps to build LLVM (macOS and Linux)
+
+### Get LLVM
+```
+git clone [LLVM]([url](https://github.com/llvm/llvm-project)https://github.com/llvm/llvm-project).
+```
+
+### Change directory to LLVM
+```
+cd llvm-project
+```
+
+### Checkout the version you want
+```
+git checkout llvmorg-15.0.7
+```
+
+### Configure LLVM
+```
+cmake -S llvm -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DLLVM_PARALLEL_{COMPILE,LINK}_JOBS=4 -DLLVM_ENABLE_PROJECTS="lld" -DLLVM_USE_LINKER=lld -DCMAKE_INSTALL_PREFIX=folder/where/you/want/to/leave/llvm
+```
+
+### Build
+```
+ninja
+```
+
+### Install
+```
+ninja install
+```
+
+### Remove unnecessary files from installation
+
+Delete:
+- All binaries, but `llvm-config` from `folder/where/you/want/to/leave/llvm/bin`
+- Remove `share` folder from `folder/where/you/want/to/leave/llvm/`
+- Remove all `.so` files from `folder/where/you/want/to/leave/llvm/lib`
+- Remove `cmake` folder from `folder/where/you/want/to/leave/llvm/lib`