diff --git a/clang/test/Analysis/padding_c.c b/clang/test/Analysis/padding_c.c
--- a/clang/test/Analysis/padding_c.c
+++ b/clang/test/Analysis/padding_c.c
@@ -12,6 +12,9 @@
 // CHECK-PAD-NEGATIVE-VALUE-SAME: 'optin.performance.Padding:AllowedPad', that
 // CHECK-PAD-NEGATIVE-VALUE-SAME: expects a non-negative value
 
+// Byval alignment warning is emitted too aggressively on AIX.
+// XFAIL: aix
+
 #if __has_include(<stdalign.h>)
 #include <stdalign.h>
 #endif
diff --git a/clang/test/Analysis/padding_cpp.cpp b/clang/test/Analysis/padding_cpp.cpp
--- a/clang/test/Analysis/padding_cpp.cpp
+++ b/clang/test/Analysis/padding_cpp.cpp
@@ -1,5 +1,8 @@
 // RUN: %clang_analyze_cc1 -std=c++14 -analyzer-checker=optin.performance -analyzer-config optin.performance.Padding:AllowedPad=2 -verify %s
 
+// Byval alignment warning is emitted too aggressively on AIX.
+// XFAIL: aix
+
 // Make sure that the C cases still work fine, even when compiled as C++.
 #include "padding_c.c"
 
diff --git a/clang/test/CXX/drs/dr6xx.cpp b/clang/test/CXX/drs/dr6xx.cpp
--- a/clang/test/CXX/drs/dr6xx.cpp
+++ b/clang/test/CXX/drs/dr6xx.cpp
@@ -4,6 +4,9 @@
 // RUN: %clang_cc1 -std=c++17 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors -fno-spell-checking
 // RUN: %clang_cc1 -std=c++20 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors -fno-spell-checking
 
+// Byval alignment warning is emitted too aggressively on AIX.
+// XFAIL: aix
+
 namespace std {
   struct type_info {};
   __extension__ typedef __SIZE_TYPE__ size_t;
diff --git a/clang/test/SemaTemplate/instantiate-attr.cpp b/clang/test/SemaTemplate/instantiate-attr.cpp
--- a/clang/test/SemaTemplate/instantiate-attr.cpp
+++ b/clang/test/SemaTemplate/instantiate-attr.cpp
@@ -1,5 +1,9 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 // expected-no-diagnostics
+
+// Byval alignment warning is emitted too aggressively on AIX.
+// XFAIL: aix
+
 template <typename T>
 struct A {
   char a __attribute__((aligned(16)));