diff --git a/compiler-rt/cmake/base-config-ix.cmake b/compiler-rt/cmake/base-config-ix.cmake
index d92bc0e71fa1a..c2a861583b9c1 100644
--- a/compiler-rt/cmake/base-config-ix.cmake
+++ b/compiler-rt/cmake/base-config-ix.cmake
@@ -109,7 +109,7 @@ if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   extend_path(default_install_path "${COMPILER_RT_INSTALL_PATH}" lib)
   set(COMPILER_RT_INSTALL_LIBRARY_DIR "${default_install_path}" CACHE PATH
     "Path where built compiler-rt libraries should be installed.")
-else(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+else()
   set(COMPILER_RT_OUTPUT_LIBRARY_DIR
     ${COMPILER_RT_OUTPUT_DIR}/lib/${COMPILER_RT_OS_DIR})
   extend_path(default_install_path "${COMPILER_RT_INSTALL_PATH}" "lib/${COMPILER_RT_OS_DIR}")
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 18b6ee85fae8d..5639061bea206 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -1190,9 +1190,9 @@ endif()
 # Build with _XOPEN_SOURCE on AIX, as stray macros in _ALL_SOURCE mode tend to
 # break things. In this case we need to enable the large-file API as well.
 if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
-          add_compile_definitions(_XOPEN_SOURCE=700)
-          add_compile_definitions(_LARGE_FILE_API)
-          add_compile_options(-pthread)
+  add_compile_definitions(_XOPEN_SOURCE=700)
+  add_compile_definitions(_LARGE_FILE_API)
+  add_compile_options(-pthread)
 
   # Modules should be built with -shared -Wl,-G, so we can use runtime linking
   # with plugins.
@@ -1200,6 +1200,13 @@ if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
 
   # Also set the correct flags for building shared libraries.
   string(APPEND CMAKE_SHARED_LINKER_FLAGS " -shared")
+
+  # Set LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF as AIX doesn't support it
+  if (LLVM_ENABLE_PER_TARGET_RUNTIME_DIR)
+    message(WARNING
+    "LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON is not supported on AIX. LLVM_ENABLE_PER_TARGET_RUNTIME_DIR is set to OFF.")
+    set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR OFF CACHE BOOL "" FORCE)
+  endif()
 endif()
 
 # Build with _XOPEN_SOURCE on z/OS.
diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
index 7f1e2ae065d6c..437dcb1365b18 100644
--- a/runtimes/CMakeLists.txt
+++ b/runtimes/CMakeLists.txt
@@ -223,6 +223,13 @@ endif()
 # This can be used to detect whether we're in the runtimes build.
 set(LLVM_RUNTIMES_BUILD ON)
 
+if (LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
+  # Set LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF as AIX doesn't support it
+  message(WARNING
+  "LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON is not supported on AIX. LLVM_ENABLE_PER_TARGET_RUNTIME_DIR is set to OFF.")
+  set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR OFF CACHE BOOL "" FORCE)
+endif()
+
 foreach(entry ${runtimes})
   get_filename_component(projName ${entry} NAME)