diff --git a/clang/include/clang/Basic/FileSystemOptions.h b/clang/include/clang/Basic/FileSystemOptions.h
index 4f3c2ae03df0..81e928da2a70 100644
--- a/clang/include/clang/Basic/FileSystemOptions.h
+++ b/clang/include/clang/Basic/FileSystemOptions.h
@@ -14,6 +14,8 @@
 #ifndef LLVM_CLANG_BASIC_FILESYSTEMOPTIONS_H
 #define LLVM_CLANG_BASIC_FILESYSTEMOPTIONS_H
 
+#include <string>
+
 namespace clang {
 
 /// \brief Keeps track of options that affect how file operations are performed.