diff --git a/test/ClangScanDeps/modules-pch-common-submodule.c b/test/ClangScanDeps/modules-pch-common-submodule.c
index 0189ab3..c7f3e76 100644
--- a/test/ClangScanDeps/modules-pch-common-submodule.c
+++ b/test/ClangScanDeps/modules-pch-common-submodule.c
@@ -1,3 +1,7 @@
+// Unsupported on AIX because we don't support the requisite "__clangast"
+// section in XCOFF yet.
+// UNSUPPORTED: aix
+
 // Check that when depending on a precompiled module, we depend on the
 // **top-level** module. Submodules don't have some information present (for
 // example the path to the modulemap file) and depending on them might cause
diff --git a/test/ClangScanDeps/modules-pch-common-via-submodule.c b/test/ClangScanDeps/modules-pch-common-via-submodule.c
index 3d35ede..e63e310 100644
--- a/test/ClangScanDeps/modules-pch-common-via-submodule.c
+++ b/test/ClangScanDeps/modules-pch-common-via-submodule.c
@@ -1,3 +1,7 @@
+// Unsupported on AIX because we don't support the requisite "__clangast"
+// section in XCOFF yet.
+// UNSUPPORTED: aix
+
 // Check that we discover dependency on a precompiled module (and generate the
 // appropriate `-fmodule-file=` argument) when it's imported by a **submodule**
 // instead of a top-level module.
diff --git a/test/ClangScanDeps/modules-pch.c b/test/ClangScanDeps/modules-pch.c
index 755ddee..2be1774 100644
--- a/test/ClangScanDeps/modules-pch.c
+++ b/test/ClangScanDeps/modules-pch.c
@@ -1,3 +1,7 @@
+// Unsupported on AIX because we don't support the requisite "__clangast"
+// section in XCOFF yet.
+// UNSUPPORTED: aix
+
 // RUN: rm -rf %t && mkdir %t
 // RUN: cp %S/Inputs/modules-pch/* %t
 
diff --git a/test/PCH/debug-info-pch-path.c b/test/PCH/debug-info-pch-path.c
index 272d9ac..192d5c7 100644
--- a/test/PCH/debug-info-pch-path.c
+++ b/test/PCH/debug-info-pch-path.c
@@ -1,3 +1,7 @@
+// Unsupported on AIX because we don't support the requisite "__clangast"
+// section in XCOFF yet.
+// UNSUPPORTED: aix
+
 // RUN: rm -rf %t
 // RUN: mkdir %t
 // RUN: cd %t