diff --git a/clang/lib/Basic/Targets/OSTargets.h b/clang/lib/Basic/Targets/OSTargets.h
--- a/clang/lib/Basic/Targets/OSTargets.h
+++ b/clang/lib/Basic/Targets/OSTargets.h
@@ -675,6 +675,13 @@
     Builder.defineMacro("_POWER");
 
     Builder.defineMacro("_AIX");
+    Builder.defineMacro("__TOS_AIX__");
+
+    if (Opts.LangStd == LangStandard::lang_c11 ||
+        Opts.LangStd == LangStandard::lang_gnu11) {
+      Builder.defineMacro("__STDC_NO_ATOMICS__");
+      Builder.defineMacro("__STDC_NO_THREADS__");
+    }
 
     if (Opts.EnableAIXExtendedAltivecABI)
       Builder.defineMacro("__EXTABI__");
diff --git a/clang/test/Preprocessor/init-ppc.c b/clang/test/Preprocessor/init-ppc.c
--- a/clang/test/Preprocessor/init-ppc.c
+++ b/clang/test/Preprocessor/init-ppc.c
@@ -541,6 +541,9 @@
 // PPC-AIX:#define __SIZE_MAX__ 4294967295UL
 // PPC-AIX:#define __SIZE_TYPE__ long unsigned int
 // PPC-AIX:#define __SIZE_WIDTH__ 32
+// PPC-AIX-NOT:#define __STDC_NO_ATOMICS__ 1
+// PPC-AIX-NOT:#define __STDC_NO_THREADS__ 1
+// PPC-AIX:#define __TOS_AIX__ 1
 // PPC-AIX:#define __UINT16_C_SUFFIX__
 // PPC-AIX:#define __UINT16_MAX__ 65535
 // PPC-AIX:#define __UINT16_TYPE__ unsigned short
@@ -723,6 +726,13 @@
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-NOTHREADSAFE %s
 // PPC-AIX-NOTHREADSAFE-NOT:#define _THREAD_SAFE 1
 
+// RUN: %clang_cc1 -x c -std=c11 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
+// RUN: %clang_cc1 -x c -std=c1x -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
+// RUN: %clang_cc1 -x c -std=iso9899:2011 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.10.0 -fno-signed-char  < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
+// RUN: %clang_cc1 -x c -std=gnu11 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char  < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
+// PPC-AIX-STDC:#define __STDC_NO_ATOMICS__ 1
+// PPC-AIX-STDC:#define __STDC_NO_THREADS__ 1
+
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-unknown-linux-gnu -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-LINUX %s
 //
 // PPC-LINUX:#define _ARCH_PPC 1