Merge from rustc

1 files changed, 12 insertions, 0 deletions

diff --git a/src/doc/unstable-book/src/compiler-flags/llvm-module-flag.md b/src/doc/unstable-book/src/compiler-flags/llvm-module-flag.md
new file mode 100644
index 00000000000..454ad0a9a6d
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags/llvm-module-flag.md
@@ -0,0 +1,12 @@
+# `llvm-module-flag`
+
+---------------------
+
+This flag allows adding a key/value to the `!llvm.module.flags` metadata in the
+LLVM-IR for a compiled Rust module.  The syntax is
+
+`-Z llvm_module_flag=<name>:<type>:<value>:<behavior>`
+
+Currently only u32 values are supported but the type is required to be specified
+for forward compatibility.  The `behavior` element must match one of the named
+LLVM [metadata behaviors](https://llvm.org/docs/LangRef.html#module-flags-metadata)