diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index 5c994734193..c53e255e1c7 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -22,6 +22,7 @@
 #include <new>
 #include <utility>
 #include <cassert>
+#include <cstddef>
 #include <cstring>
 
 namespace llvm {
diff --git a/include/llvm/ADT/SmallVector.h b/include/llvm/ADT/SmallVector.h
index e4fa809abdf..b966864515e 100644
--- a/include/llvm/ADT/SmallVector.h
+++ b/include/llvm/ADT/SmallVector.h
@@ -17,6 +17,7 @@
 #include "llvm/Support/type_traits.h"
 #include <algorithm>
 #include <cassert>
+#include <cstddef>
 #include <cstdlib>
 #include <cstring>
 #include <memory>
diff --git a/include/llvm/ADT/ilist.h b/include/llvm/ADT/ilist.h
index e4d26ddfa50..9479d00f31b 100644
--- a/include/llvm/ADT/ilist.h
+++ b/include/llvm/ADT/ilist.h
@@ -39,6 +39,7 @@
 #define LLVM_ADT_ILIST_H
 
 #include <cassert>
+#include <cstddef>
 #include <iterator>
 
 namespace llvm {
diff --git a/include/llvm/Use.h b/include/llvm/Use.h
index 970f69b9da8..2759338f42a 100644
--- a/include/llvm/Use.h
+++ b/include/llvm/Use.h
@@ -27,6 +27,7 @@
 
 #include "llvm/Support/Casting.h"
 #include "llvm/ADT/PointerIntPair.h"
+#include <cstddef>
 #include <iterator>
 
 namespace llvm {