diff --git a/gcc/testsuite/gcc.dg/atomic/c2x-stdatomic-lockfree-char8_t.c b/gcc/testsuite/gcc.dg/atomic/c2x-stdatomic-lockfree-char8_t.c
new file mode 100644
index 00000000000..1b692f55ed0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/atomic/c2x-stdatomic-lockfree-char8_t.c
@@ -0,0 +1,42 @@
+/* Test atomic_is_lock_free for char8_t.  */
+/* { dg-do run } */
+/* { dg-options "-std=c2x -pedantic-errors" } */
+
+#include <stdatomic.h>
+#include <stdint.h>
+
+extern void abort (void);
+
+_Atomic __CHAR8_TYPE__ ac8a;
+atomic_char8_t ac8t;
+
+#define CHECK_TYPE(MACRO, V1, V2)		\
+  do						\
+    {						\
+      int r1 = MACRO;				\
+      int r2 = atomic_is_lock_free (&V1);	\
+      int r3 = atomic_is_lock_free (&V2);	\
+      if (r1 != 0 && r1 != 1 && r1 != 2)	\
+	abort ();				\
+      if (r2 != 0 && r2 != 1)			\
+	abort ();				\
+      if (r3 != 0 && r3 != 1)			\
+	abort ();				\
+      if (r1 == 2 && r2 != 1)			\
+	abort ();				\
+      if (r1 == 2 && r3 != 1)			\
+	abort ();				\
+      if (r1 == 0 && r2 != 0)			\
+	abort ();				\
+      if (r1 == 0 && r3 != 0)			\
+	abort ();				\
+    }						\
+  while (0)
+
+int
+main ()
+{
+  CHECK_TYPE (ATOMIC_CHAR8_T_LOCK_FREE, ac8a, ac8t);
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/atomic/gnu2x-stdatomic-lockfree-char8_t.c b/gcc/testsuite/gcc.dg/atomic/gnu2x-stdatomic-lockfree-char8_t.c
new file mode 100644
index 00000000000..27a3cfe3552
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/atomic/gnu2x-stdatomic-lockfree-char8_t.c
@@ -0,0 +1,5 @@
+/* Test atomic_is_lock_free for char8_t with -std=gnu2x.  */
+/* { dg-do run } */
+/* { dg-options "-std=gnu2x -pedantic-errors" } */
+
+#include "c2x-stdatomic-lockfree-char8_t.c"
diff --git a/gcc/testsuite/gcc.dg/c11-utf8str-type.c b/gcc/testsuite/gcc.dg/c11-utf8str-type.c
new file mode 100644
index 00000000000..8be9abb9686
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c11-utf8str-type.c
@@ -0,0 +1,6 @@
+/* Test C11 UTF-8 string literal type.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c11" } */
+
+_Static_assert (_Generic (u8"text", char*: 1, default: 2) == 1, "UTF-8 string literals have an unexpected type");
+_Static_assert (_Generic (u8"x"[0], char:  1, default: 2) == 1, "UTF-8 string literal elements have an unexpected type");
diff --git a/gcc/testsuite/gcc.dg/c17-utf8str-type.c b/gcc/testsuite/gcc.dg/c17-utf8str-type.c
new file mode 100644
index 00000000000..515c6db3970
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c17-utf8str-type.c
@@ -0,0 +1,6 @@
+/* Test C17 UTF-8 string literal type.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c17" } */
+
+_Static_assert (_Generic (u8"text", char*: 1, default: 2) == 1, "UTF-8 string literals have an unexpected type");
+_Static_assert (_Generic (u8"x"[0], char:  1, default: 2) == 1, "UTF-8 string literal elements have an unexpected type");
diff --git a/gcc/testsuite/gcc.dg/c2x-predefined-macros.c b/gcc/testsuite/gcc.dg/c2x-predefined-macros.c
new file mode 100644
index 00000000000..3456105563a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-predefined-macros.c
@@ -0,0 +1,11 @@
+/* Test C2X predefined macros.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c2x" } */
+
+#if !defined(__CHAR8_TYPE__)
+# error __CHAR8_TYPE__ is not defined!
+#endif
+
+#if !defined(__GCC_ATOMIC_CHAR8_T_LOCK_FREE)
+# error __GCC_ATOMIC_CHAR8_T_LOCK_FREE is not defined!
+#endif
diff --git a/gcc/testsuite/gcc.dg/c2x-utf8str-type.c b/gcc/testsuite/gcc.dg/c2x-utf8str-type.c
new file mode 100644
index 00000000000..ebdde97b57a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-utf8str-type.c
@@ -0,0 +1,6 @@
+/* Test C2X UTF-8 string literal type.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c2x" } */
+
+_Static_assert (_Generic (u8"text", unsigned char*: 1, default: 2) == 1, "UTF-8 string literals have an unexpected type");
+_Static_assert (_Generic (u8"x"[0], unsigned char:  1, default: 2) == 1, "UTF-8 string literal elements have an unexpected type");
diff --git a/gcc/testsuite/gcc.dg/c2x-utf8str.c b/gcc/testsuite/gcc.dg/c2x-utf8str.c
new file mode 100644
index 00000000000..2e4c392da9f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-utf8str.c
@@ -0,0 +1,34 @@
+/* Test initialization by UTF-8 string literal in C2X.  */
+/* { dg-do compile } */
+/* { dg-require-effective-target wchar } */
+/* { dg-options "-std=c2x" } */
+
+typedef __CHAR8_TYPE__  char8_t;
+typedef __CHAR16_TYPE__ char16_t;
+typedef __CHAR32_TYPE__ char32_t;
+typedef __WCHAR_TYPE__  wchar_t;
+
+/* Test that char, signed char, unsigned char, and char8_t arrays can be
+   initialized by a UTF-8 string literal.  */
+const char cbuf1[] = u8"text";
+const char cbuf2[] = { u8"text" };
+const signed char scbuf1[] = u8"text";
+const signed char scbuf2[] = { u8"text" };
+const unsigned char ucbuf1[] = u8"text";
+const unsigned char ucbuf2[] = { u8"text" };
+const char8_t c8buf1[] = u8"text";
+const char8_t c8buf2[] = { u8"text" };
+
+/* Test that a diagnostic is issued for attempted initialization of
+   other character types by a UTF-8 string literal.  */
+const char16_t c16buf1[] = u8"text";		/* { dg-error "from a string literal with type array of .unsigned char." } */
+const char16_t c16buf2[] = { u8"text" };	/* { dg-error "from a string literal with type array of .unsigned char." } */
+const char32_t c32buf1[] = u8"text";		/* { dg-error "from a string literal with type array of .unsigned char." } */
+const char32_t c32buf2[] = { u8"text" };	/* { dg-error "from a string literal with type array of .unsigned char." } */
+const wchar_t wbuf1[] = u8"text";		/* { dg-error "from a string literal with type array of .unsigned char." } */
+const wchar_t wbuf2[] = { u8"text" };		/* { dg-error "from a string literal with type array of .unsigned char." } */
+
+/* Test that char8_t arrays can be initialized by an ordinary string
+   literal.  */
+const char8_t c8buf3[] = "text";
+const char8_t c8buf4[] = { "text" };
diff --git a/gcc/testsuite/gcc.dg/gnu2x-predefined-macros.c b/gcc/testsuite/gcc.dg/gnu2x-predefined-macros.c
new file mode 100644
index 00000000000..f1906cdf73c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu2x-predefined-macros.c
@@ -0,0 +1,5 @@
+/* Test C2X predefined macros with -std=gnu2x.  */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu2x" } */
+
+#include "c2x-predefined-macros.c"
diff --git a/gcc/testsuite/gcc.dg/gnu2x-utf8str-type.c b/gcc/testsuite/gcc.dg/gnu2x-utf8str-type.c
new file mode 100644
index 00000000000..efe16ffc28d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu2x-utf8str-type.c
@@ -0,0 +1,5 @@
+/* Test C2X UTF-8 string literal type with -std=gnu2x.  */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu2x" } */
+
+#include "c2x-utf8str-type.c"
diff --git a/gcc/testsuite/gcc.dg/gnu2x-utf8str.c b/gcc/testsuite/gcc.dg/gnu2x-utf8str.c
new file mode 100644
index 00000000000..f3719ea8c77
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu2x-utf8str.c
@@ -0,0 +1,34 @@
+/* Test initialization by UTF-8 string literal in C2X with -std=gnu2x.  */
+/* { dg-do compile } */
+/* { dg-require-effective-target wchar } */
+/* { dg-options "-std=gnu2x" } */
+
+typedef __CHAR8_TYPE__  char8_t;
+typedef __CHAR16_TYPE__ char16_t;
+typedef __CHAR32_TYPE__ char32_t;
+typedef __WCHAR_TYPE__  wchar_t;
+
+/* Test that char, signed char, unsigned char, and char8_t arrays can be
+   initialized by a UTF-8 string literal.  */
+const char cbuf1[] = u8"text";
+const char cbuf2[] = { u8"text" };
+const signed char scbuf1[] = u8"text";
+const signed char scbuf2[] = { u8"text" };
+const unsigned char ucbuf1[] = u8"text";
+const unsigned char ucbuf2[] = { u8"text" };
+const char8_t c8buf1[] = u8"text";
+const char8_t c8buf2[] = { u8"text" };
+
+/* Test that a diagnostic is issued for attempted initialization of
+   other character types by a UTF-8 string literal.  */
+const char16_t c16buf1[] = u8"text";		/* { dg-error "from a string literal with type array of .unsigned char." } */
+const char16_t c16buf2[] = { u8"text" };	/* { dg-error "from a string literal with type array of .unsigned char." } */
+const char32_t c32buf1[] = u8"text";		/* { dg-error "from a string literal with type array of .unsigned char." } */
+const char32_t c32buf2[] = { u8"text" };	/* { dg-error "from a string literal with type array of .unsigned char." } */
+const wchar_t wbuf1[] = u8"text";		/* { dg-error "from a string literal with type array of .unsigned char." } */
+const wchar_t wbuf2[] = { u8"text" };		/* { dg-error "from a string literal with type array of .unsigned char." } */
+
+/* Test that char8_t arrays can be initialized by an ordinary string
+   literal.  */
+const char8_t c8buf3[] = "text";
+const char8_t c8buf4[] = { "text" };
