https://bugs.gentoo.org/985264

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -241,6 +241,7 @@ if (TARGET clang-resource-headers)
   add_dependencies(include-what-you-use clang-resource-headers)
 endif()
 
+if (BUILD_TESTS)
 if (IWYU_USE_SYSTEM_GTEST)
   message(STATUS "IWYU: using system gtest")
   find_package(GTest CONFIG REQUIRED)
@@ -324,6 +325,7 @@ add_custom_target(iwyu-run-unittests
   COMMAND $<TARGET_FILE:iwyu-unittests>
   USES_TERMINAL
 )
+endif()
 
 # Install programs.
 include(GNUInstallDirs)
@@ -364,6 +366,8 @@ if (NOT iwyu_standalone_build)
   )
 endif()  
 
+
+if (BUILD_TESTS)
 find_package(Python3 COMPONENTS Interpreter)
 if (Python3_Interpreter_FOUND)
   # Map the various IWYU test scripts to CTest tests.
@@ -396,3 +400,4 @@ if (Python3_Interpreter_FOUND)
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
   )
 endif()
+endif()