diff --git a/stdlib/public/Cxx/CxxConvertibleToCollection.swift b/stdlib/public/Cxx/CxxConvertibleToCollection.swift
index 495b9758ff3da..976bd270d0daa 100644
--- a/stdlib/public/Cxx/CxxConvertibleToCollection.swift
+++ b/stdlib/public/Cxx/CxxConvertibleToCollection.swift
@@ -45,6 +45,7 @@ extension RangeReplaceableCollection {
   ///   container when each element is copied in O(1). Note that this might not
   ///   be true for certain C++ types, e.g. those with a custom copy
   ///   constructor that performs additional logic.
+  @inlinable
   public init<C: CxxConvertibleToCollection>(_ elements: C)
     where C.RawIterator.Pointee == Element {
 
@@ -62,6 +63,7 @@ extension SetAlgebra {
   ///   container when each element is copied in O(1). Note that this might not
   ///   be true for certain C++ types, e.g. those with a custom copy
   ///   constructor that performs additional logic.
+  @inlinable
   public init<C: CxxConvertibleToCollection>(_ elements: C)
     where C.RawIterator.Pointee == Element {
 
diff --git a/stdlib/public/Cxx/CxxSet.swift b/stdlib/public/Cxx/CxxSet.swift
index 393ad4b78d5c1..02dec94fb1193 100644
--- a/stdlib/public/Cxx/CxxSet.swift
+++ b/stdlib/public/Cxx/CxxSet.swift
@@ -18,6 +18,7 @@ public protocol CxxSet<Element> {
 }
 
 extension CxxSet {
+  @inlinable
   public func contains(_ element: Element) -> Bool {
     return count(element) > 0
   }