diff --git a/llvm/lib/Testing/Support/CMakeLists.txt b/llvm/lib/Testing/Support/CMakeLists.txt
--- a/llvm/lib/Testing/Support/CMakeLists.txt
+++ b/llvm/lib/Testing/Support/CMakeLists.txt
@@ -1,3 +1,7 @@
+# Do not build unittest libraries automatically, they will be pulled in
+# by unittests if these are built.
+set(EXCLUDE_FROM_ALL ON)
+
 add_llvm_library(LLVMTestingSupport
   Annotations.cpp
   Error.cpp
diff --git a/third-party/unittest/CMakeLists.txt b/third-party/unittest/CMakeLists.txt
--- a/third-party/unittest/CMakeLists.txt
+++ b/third-party/unittest/CMakeLists.txt
@@ -38,6 +38,10 @@
   list(APPEND LIBS pthread)
 endif()
 
+# Do not build unittest libraries automatically, they will be pulled in
+# by unittests if these are built.
+set(EXCLUDE_FROM_ALL ON)
+
 add_llvm_library(llvm_gtest
   googletest/src/gtest-all.cc
   googlemock/src/gmock-all.cc