Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -3409,6 +3409,10 @@
 
 Unrolling of a loop can be prevented by specifying ``unroll(disable)``.
 
+Fully unrolling loops can cause excessive compilation time. LLVM options
+`-unroll-count=n` and `-pragma-unroll-threshold=n` can be used to control loop
+unrolling specified by pragmas, including `#pragma unroll` directives.
+
 Loop Distribution
 -----------------