diff --git a/compiler/rustc_serialize/src/leb128.rs b/compiler/rustc_serialize/src/leb128.rs
index c5297bff193..7dad9aa01fa 100644
--- a/compiler/rustc_serialize/src/leb128.rs
+++ b/compiler/rustc_serialize/src/leb128.rs
@@ -1,11 +1,11 @@
-/// Returns the longest LEB128 encoding for `T`, assuming `T` is an integer type
+/// Returns the length of the longest LEB128 encoding for `T`, assuming `T` is an integer type
 pub const fn max_leb128_len<T>() -> usize {
     // The longest LEB128 encoding for an integer uses 7 bits per byte.
     (std::mem::size_of::<T>() * 8 + 6) / 7
 }
 
-/// Returns the longest LEB128 encoding of all supported integer types.
-pub const fn max_max_leb128_len() -> usize {
+/// Returns the length of the longest LEB128 encoding of all supported integer types.
+pub const fn largest_max_leb128_len() -> usize {
     max_leb128_len::<u128>()
 }
 
diff --git a/compiler/rustc_serialize/src/opaque.rs b/compiler/rustc_serialize/src/opaque.rs
index 7cd513e1eb9..0afeb86fceb 100644
--- a/compiler/rustc_serialize/src/opaque.rs
+++ b/compiler/rustc_serialize/src/opaque.rs
@@ -1,4 +1,4 @@
-use crate::leb128::{self, max_max_leb128_len};
+use crate::leb128::{self, largest_max_leb128_len};
 use crate::serialize::{Decodable, Decoder, Encodable, Encoder};
 use std::convert::TryInto;
 use std::fs::File;
@@ -186,12 +186,12 @@ pub fn new<P: AsRef<Path>>(path: P) -> io::Result<Self> {
     pub fn with_capacity<P: AsRef<Path>>(path: P, capacity: usize) -> io::Result<Self> {
         // Require capacity at least as large as the largest LEB128 encoding
         // here, so that we don't have to check or handle this on every write.
-        assert!(capacity >= max_max_leb128_len());
+        assert!(capacity >= largest_max_leb128_len());
 
         // Require capacity small enough such that some capacity checks can be
         // done using guaranteed non-overflowing add rather than sub, which
         // shaves an instruction off those code paths (on x86 at least).
-        assert!(capacity <= usize::MAX - max_max_leb128_len());
+        assert!(capacity <= usize::MAX - largest_max_leb128_len());
 
         // Create the file for reading and writing, because some encoders do both
         // (e.g. the metadata encoder when -Zmeta-stats is enabled)