Index: .gitignore
===================================================================
--- /dev/null
+++ .gitignore
@@ -0,0 +1,25 @@
+# Ignore any files outside of the project directories so that users can store
+# their build directories here without them being considered untracked.
+
+/*
+!/.arcconfig
+!/.clang-format
+!/.clang-tidy
+!/.gitignore
+!/README.md
+!/clang
+!/clang-tools-extra
+!/compiler-rt
+!/debuginfo-tests
+!/libclc
+!/libcxx
+!/libcxxabi
+!/libunwind
+!/lld
+!/lldb
+!/llgo
+!/llvm
+!/openmp
+!/parallel-libs
+!/polly
+!/pstl