diff --git a/lib/libcxx/include/__config b/lib/libcxx/include/__config
index d9a47343da..0aab23b9b4 100644
--- a/lib/libcxx/include/__config
+++ b/lib/libcxx/include/__config
@@ -148,7 +148,7 @@
 #    endif
 // Feature macros for disabling pre ABI v1 features. All of these options
 // are deprecated.
-#    if defined(__FreeBSD__)
+#    if defined(__FreeBSD__) || defined(__DragonFly__)
 #      define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 #    endif
 #  endif
@@ -726,11 +726,11 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
 #  endif // _LIBCPP_CXX03_LANG
 
 #  if defined(__APPLE__) || defined(__FreeBSD__) || defined(_LIBCPP_MSVCRT_LIKE) || defined(__sun__) ||                \
-      defined(__NetBSD__)
+      defined(__NetBSD__) || defined(__DragonFly__)
 #    define _LIBCPP_LOCALE__L_EXTENSIONS 1
 #  endif
 
-#  ifdef __FreeBSD__
+#  if defined(__FreeBSD__) || defined(__DragonFly__)
 #    define _DECLARE_C99_LDBL_MATH 1
 #  endif
 
@@ -750,11 +750,11 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
 #    define _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
 #  endif
 
-#  if defined(__APPLE__) || defined(__FreeBSD__)
+#  if defined(__APPLE__) || defined(__FreeBSD__) || defined(__DragonFly__)
 #    define _LIBCPP_HAS_DEFAULTRUNELOCALE
 #  endif
 
-#  if defined(__APPLE__) || defined(__FreeBSD__) || defined(__sun__)
+#  if defined(__APPLE__) || defined(__FreeBSD__) || defined(__sun__) || defined(__DragonFly__)
 #    define _LIBCPP_WCTYPE_IS_MASK
 #  endif
 
@@ -901,6 +901,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
 
 #    if defined(__FreeBSD__) ||                                                                                        \
         defined(__wasi__) ||                                                                                           \
+        defined(__DragonFly__) ||                                                                                      \
         defined(__NetBSD__) ||                                                                                         \
         defined(__OpenBSD__) ||                                                                                        \
         defined(__NuttX__) ||                                                                                          \
diff --git a/lib/libcxx/include/__locale b/lib/libcxx/include/__locale
index 40f9a3ff57..62a439b979 100644
--- a/lib/libcxx/include/__locale
+++ b/lib/libcxx/include/__locale
@@ -33,7 +33,7 @@
 # include <__support/newlib/xlocale.h>
 #elif defined(__OpenBSD__)
 # include <__support/openbsd/xlocale.h>
-#elif (defined(__APPLE__) || defined(__FreeBSD__))
+#elif (defined(__APPLE__) || defined(__FreeBSD__) || defined(__DragonFly__))
 # include <xlocale.h>
 #elif defined(__Fuchsia__)
 # include <__support/fuchsia/xlocale.h>
@@ -453,10 +453,10 @@ public:
     static const mask __regex_word = 0x4000; // 0x8000 and 0x0100 and 0x00ff are used
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
-#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
+#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__) || defined(__DragonFly__)
 # ifdef __APPLE__
     typedef __uint32_t mask;
-# elif defined(__FreeBSD__)
+# elif defined(__FreeBSD__) || defined(__DragonFly__)
     typedef unsigned long mask;
 # elif defined(__EMSCRIPTEN__) || defined(__NetBSD__)
     typedef unsigned short mask;
diff --git a/lib/libcxx/include/locale b/lib/libcxx/include/locale
index b01c66d043..de37d35a69 100644
--- a/lib/libcxx/include/locale
+++ b/lib/libcxx/include/locale
@@ -239,7 +239,7 @@ _LIBCPP_PUSH_MACROS
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if defined(__APPLE__) || defined(__FreeBSD__)
+#if defined(__APPLE__) || defined(__FreeBSD__) || defined(__DragonFly__)
 #  define _LIBCPP_GET_C_LOCALE 0
 #elif defined(__NetBSD__)
 #  define _LIBCPP_GET_C_LOCALE LC_C_LOCALE
diff --git a/lib/libcxx/src/locale.cpp b/lib/libcxx/src/locale.cpp
index 6b454274e1..dc4ee7cbd9 100644
--- a/lib/libcxx/src/locale.cpp
+++ b/lib/libcxx/src/locale.cpp
@@ -1190,7 +1190,7 @@ ctype<char>::classic_table() noexcept
 const ctype<char>::mask*
 ctype<char>::classic_table() noexcept
 {
-#if defined(__APPLE__) || defined(__FreeBSD__)
+#if defined(__APPLE__) || defined(__FreeBSD__) || defined(__DragonFly__)
     return _DefaultRuneLocale.__runetype;
 #elif defined(__NetBSD__)
     return _C_ctype_tab_ + 1;