diff --git a/llvm/docs/CodingStandards.rst b/llvm/docs/CodingStandards.rst
--- a/llvm/docs/CodingStandards.rst
+++ b/llvm/docs/CodingStandards.rst
@@ -86,7 +86,8 @@
 there isn't a specific reason to favor the C++ implementation, it is generally
 preferable to use the LLVM library. For example, ``llvm::DenseMap`` should
 almost always be used instead of ``std::map`` or ``std::unordered_map``, and
-``llvm::SmallVector`` should usually be used instead of ``std::vector``.
+``llvm::SmallVector`` should be used instead of ``std::vector`` when the small
+size optimization makes sense.
 
 We explicitly avoid some standard facilities, like the I/O streams, and instead
 use LLVM's streams library (raw_ostream_). More detailed information on these