diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -511,10 +511,10 @@
 # Required flags ==============================================================
 function(cxx_add_basic_build_flags target)
 
-  # Require C++17 for all targets. C++17 is needed to use aligned allocation
-  # in the dylib.
+  # Require C++20 for all targets. C++17 is needed to use aligned allocation
+  # in the dylib. C++20 is needed to use char8_t.
   set_target_properties(${target} PROPERTIES
-    CXX_STANDARD 17
+    CXX_STANDARD 20
     CXX_STANDARD_REQUIRED YES
     CXX_EXTENSIONS NO)
 
diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt
--- a/libcxxabi/src/CMakeLists.txt
+++ b/libcxxabi/src/CMakeLists.txt
@@ -174,7 +174,7 @@
                           CXX_EXTENSIONS
                             OFF
                           CXX_STANDARD
-                            17
+                            20
                           CXX_STANDARD_REQUIRED
                             ON
                           COMPILE_FLAGS
@@ -241,7 +241,7 @@
                           CXX_EXTENSIONS
                             OFF
                           CXX_STANDARD
-                            17
+                            20
                           CXX_STANDARD_REQUIRED
                             ON
                           COMPILE_FLAGS