diff --git a/compiler-rt/cmake/base-config-ix.cmake b/compiler-rt/cmake/base-config-ix.cmake
--- a/compiler-rt/cmake/base-config-ix.cmake
+++ b/compiler-rt/cmake/base-config-ix.cmake
@@ -5,9 +5,14 @@
 
 include(CheckIncludeFile)
 include(CheckCXXSourceCompiles)
-include(GNUInstallDirs)
 include(ExtendPath)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
+include(GNUInstallDirs)
+
 check_include_file(unwind.h HAVE_UNWIND_H)
 
 # Used by sanitizer_common and tests.
diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -7,6 +7,10 @@
 set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 set(FLANG_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -10,6 +10,10 @@
 #===============================================================================
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -10,6 +10,10 @@
 
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
diff --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -8,6 +8,10 @@
 
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
diff --git a/lld/CMakeLists.txt b/lld/CMakeLists.txt
--- a/lld/CMakeLists.txt
+++ b/lld/CMakeLists.txt
@@ -1,5 +1,9 @@
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 # If we are not building as a part of LLVM, build LLD as an
diff --git a/lldb/CMakeLists.txt b/lldb/CMakeLists.txt
--- a/lldb/CMakeLists.txt
+++ b/lldb/CMakeLists.txt
@@ -1,5 +1,9 @@
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 # Add path for custom modules.
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -2,6 +2,10 @@
 
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 # CMP0116: Ninja generators transform `DEPFILE`s from `add_custom_command()`
diff --git a/polly/CMakeLists.txt b/polly/CMakeLists.txt
--- a/polly/CMakeLists.txt
+++ b/polly/CMakeLists.txt
@@ -1,3 +1,7 @@
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 # Check if this is a in tree build.
diff --git a/pstl/CMakeLists.txt b/pstl/CMakeLists.txt
--- a/pstl/CMakeLists.txt
+++ b/pstl/CMakeLists.txt
@@ -7,6 +7,10 @@
 #===----------------------------------------------------------------------===##
 cmake_minimum_required(VERSION 3.13.4)
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+  # No suffixes by default: LLVM does those separately.
+  set(CMAKE_INSTALL_LIBDIR lib)
+endif()
 include(GNUInstallDirs)
 
 set(PARALLELSTL_VERSION_FILE "${CMAKE_CURRENT_SOURCE_DIR}/include/pstl/internal/pstl_config.h")