diff --git a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
--- a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
+++ b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
@@ -10,9 +10,6 @@
 // is required for users to be able to include any public header and then override
 // the function using a strong definition.
 
-// The system-provided <uchar.h> seems to be broken on AIX, which trips up this test.
-// XFAIL: LIBCXX-AIX-FIXME
-
 // XFAIL: availability-verbose_abort-missing
 
 /*
diff --git a/libcxx/test/libcxx/double_include.sh.cpp b/libcxx/test/libcxx/double_include.sh.cpp
--- a/libcxx/test/libcxx/double_include.sh.cpp
+++ b/libcxx/test/libcxx/double_include.sh.cpp
@@ -13,9 +13,6 @@
 // RUN: %{cxx} -o %t.exe %t.first.o %t.second.o %{flags} %{link_flags}
 // RUN: %{run}
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED
diff --git a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
--- a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
+++ b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
@@ -9,9 +9,6 @@
 // Test that headers are not tripped up by the surrounding code defining the
 // min() and max() macros.
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED
diff --git a/libcxx/test/libcxx/modules_include.sh.cpp b/libcxx/test/libcxx/modules_include.sh.cpp
--- a/libcxx/test/libcxx/modules_include.sh.cpp
+++ b/libcxx/test/libcxx/modules_include.sh.cpp
@@ -10,9 +10,6 @@
 // This is important notably because the LLDB data formatters use
 // libc++ headers with modules enabled.
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // GCC doesn't support -fcxx-modules
 // UNSUPPORTED: gcc
 
diff --git a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
--- a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
+++ b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
@@ -9,9 +9,6 @@
 // Test that headers are not tripped up by the surrounding code defining various
 // alphabetic macros.
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED
diff --git a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
--- a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
+++ b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
@@ -9,9 +9,6 @@
 // Ensure that none of the standard C++ headers implicitly include cassert or
 // assert.h (because assert() is implemented as a macro).
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED
diff --git a/libcxx/test/libcxx/strings/c.strings/version_cuchar.pass.cpp b/libcxx/test/libcxx/strings/c.strings/version_cuchar.pass.cpp
--- a/libcxx/test/libcxx/strings/c.strings/version_cuchar.pass.cpp
+++ b/libcxx/test/libcxx/strings/c.strings/version_cuchar.pass.cpp
@@ -8,9 +8,6 @@
 
 // UNSUPPORTED: c++03
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // <cuchar>
 
 #include <cuchar>
diff --git a/libcxx/test/std/depr/depr.c.headers/uchar_h.compile.pass.cpp b/libcxx/test/std/depr/depr.c.headers/uchar_h.compile.pass.cpp
--- a/libcxx/test/std/depr/depr.c.headers/uchar_h.compile.pass.cpp
+++ b/libcxx/test/std/depr/depr.c.headers/uchar_h.compile.pass.cpp
@@ -11,9 +11,6 @@
 // Apple platforms don't provide <uchar.h> yet, so these tests fail.
 // XFAIL: target={{.+}}-apple-{{.+}}
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // <uchar.h>
 
 #include <uchar.h>
diff --git a/libcxx/test/std/strings/c.strings/cuchar.compile.pass.cpp b/libcxx/test/std/strings/c.strings/cuchar.compile.pass.cpp
--- a/libcxx/test/std/strings/c.strings/cuchar.compile.pass.cpp
+++ b/libcxx/test/std/strings/c.strings/cuchar.compile.pass.cpp
@@ -11,9 +11,6 @@
 // Apple platforms don't provide <uchar.h> yet, so these tests fail.
 // XFAIL: target={{.+}}-apple-{{.+}}
 
-// The system-provided <uchar.h> seems to be broken on AIX
-// XFAIL: LIBCXX-AIX-FIXME
-
 // <cuchar>
 
 #include <cuchar>
diff --git a/libcxx/test/std/strings/c.strings/no_c8rtomb_mbrtoc8.verify.cpp b/libcxx/test/std/strings/c.strings/no_c8rtomb_mbrtoc8.verify.cpp
--- a/libcxx/test/std/strings/c.strings/no_c8rtomb_mbrtoc8.verify.cpp
+++ b/libcxx/test/std/strings/c.strings/no_c8rtomb_mbrtoc8.verify.cpp
@@ -8,13 +8,6 @@
 
 // UNSUPPORTED: c++03
 
-// The system-provided <uchar.h> seems to be broken on AIX:
-//   error: 'error' diagnostics seen but not expected:
-//     File /usr/include/uchar.h Line 38: cannot combine with previous 'type-name' declaration specifier
-//     File /usr/include/uchar.h Line 39: cannot combine with previous 'type-name' declaration specifier
-//   2 errors generated.
-// XFAIL: LIBCXX-AIX-FIXME
-
 #include <uchar.h>
 
 #include "test_macros.h"