diff --git a/src/doc/unstable-book/src/compiler-flags/self-profile-events.md b/src/doc/unstable-book/src/compiler-flags/self-profile-events.md
index b7d60409e00..3e644f786f6 100644
--- a/src/doc/unstable-book/src/compiler-flags/self-profile-events.md
+++ b/src/doc/unstable-book/src/compiler-flags/self-profile-events.md
@@ -41,7 +41,7 @@ $ rustc -Zself-profile -Zself-profile-events=default,args
 
 - `llvm`
   - Adds tracing information about LLVM passes and codegeneration.
-  - Disabled by default for historical reasons.
+  - Disabled by default because this significantly increases the trace file size.
 
 ## Event synonyms