diff --git a/lib/Fuzzer/CMakeLists.txt b/lib/Fuzzer/CMakeLists.txt
index 499cf98a6b9..a68df7f0feb 100644
--- a/lib/Fuzzer/CMakeLists.txt
+++ b/lib/Fuzzer/CMakeLists.txt
@@ -1,15 +1,17 @@
 # Disable the coverage instrumentation for the fuzzer itself.
 set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O2 -fsanitize-coverage=0")
 if( LLVM_USE_SANITIZE_COVERAGE  )
-  add_library(LLVMFuzzer STATIC
-    EXCLUDE_FROM_ALL  # Do not build if you are not building fuzzers.
+  add_library(LLVMFuzzerNoMain OBJECT
     FuzzerCrossOver.cpp
     FuzzerIO.cpp
     FuzzerLoop.cpp
-    FuzzerMain.cpp
     FuzzerMutate.cpp
     FuzzerUtil.cpp
     )
+  add_library(LLVMFuzzer STATIC
+    FuzzerMain.cpp
+    $<TARGET_OBJECTS:LLVMFuzzerNoMain>
+    )
 
   if( LLVM_INCLUDE_TESTS )
     add_subdirectory(test)
diff --git a/lib/Fuzzer/test/CMakeLists.txt b/lib/Fuzzer/test/CMakeLists.txt
index 17afd92c3b4..2b94b4b49ae 100644
--- a/lib/Fuzzer/test/CMakeLists.txt
+++ b/lib/Fuzzer/test/CMakeLists.txt
@@ -25,19 +25,36 @@ foreach(Test ${Tests})
   set(TestBinaries ${TestBinaries} LLVMFuzzer-${Test})
 endforeach()
 
-set_target_properties(${TestBinaries}
-  PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
-  )
-
-set(EXCLUDE_FROM_ALL TRUE)
-add_lit_testsuite(check-fuzzer "Running Fuzzer tests"
-    ${CMAKE_CURRENT_BINARY_DIR}
-    DEPENDS ${TestBinaries}
-    )
-set(EXCLUDE_FROM_ALL FALSE)
-
 configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
   )
 
+configure_lit_site_cfg(
+  ${CMAKE_CURRENT_SOURCE_DIR}/unit/lit.site.cfg.in
+  ${CMAKE_CURRENT_BINARY_DIR}/unit/lit.site.cfg
+  )
+
+include_directories(..)
+include_directories(${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include)
+
+add_executable(LLVMFuzzer-Unittest
+  FuzzerUnittest.cpp
+  $<TARGET_OBJECTS:LLVMFuzzerNoMain>
+  )
+
+target_link_libraries(LLVMFuzzer-Unittest
+  gtest
+  gtest_main
+  )
+
+set(TestBinaries ${TestBinaries} LLVMFuzzer-Unittest)
+
+set_target_properties(${TestBinaries}
+  PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+  )
+
+add_lit_testsuite(check-fuzzer "Running Fuzzer tests"
+    ${CMAKE_CURRENT_BINARY_DIR}
+    DEPENDS ${TestBinaries}
+    )
diff --git a/lib/Fuzzer/test/FuzzerUnittest.cpp b/lib/Fuzzer/test/FuzzerUnittest.cpp
new file mode 100644
index 00000000000..368a0f2bf00
--- /dev/null
+++ b/lib/Fuzzer/test/FuzzerUnittest.cpp
@@ -0,0 +1,62 @@
+#include "FuzzerInternal.h"
+#include "gtest/gtest.h"
+#include <set>
+
+// For now, have TestOneInput just to make it link.
+// Later we may want to make unittests that actually call TestOneInput.
+extern "C" void TestOneInput(const uint8_t *Data, size_t Size) {
+  abort();
+}
+
+TEST(Fuzzer, CrossOver) {
+  using namespace fuzzer;
+  Unit A({0, 1, 2}), B({5, 6, 7});
+  Unit C;
+  Unit Expected[] = {
+       { 0 },
+       { 0, 1 },
+       { 0, 5 },
+       { 0, 1, 2 },
+       { 0, 1, 5 },
+       { 0, 5, 1 },
+       { 0, 5, 6 },
+       { 0, 1, 2, 5 },
+       { 0, 1, 5, 2 },
+       { 0, 1, 5, 6 },
+       { 0, 5, 1, 2 },
+       { 0, 5, 1, 6 },
+       { 0, 5, 6, 1 },
+       { 0, 5, 6, 7 },
+       { 0, 1, 2, 5, 6 },
+       { 0, 1, 5, 2, 6 },
+       { 0, 1, 5, 6, 2 },
+       { 0, 1, 5, 6, 7 },
+       { 0, 5, 1, 2, 6 },
+       { 0, 5, 1, 6, 2 },
+       { 0, 5, 1, 6, 7 },
+       { 0, 5, 6, 1, 2 },
+       { 0, 5, 6, 1, 7 },
+       { 0, 5, 6, 7, 1 },
+       { 0, 1, 2, 5, 6, 7 },
+       { 0, 1, 5, 2, 6, 7 },
+       { 0, 1, 5, 6, 2, 7 },
+       { 0, 1, 5, 6, 7, 2 },
+       { 0, 5, 1, 2, 6, 7 },
+       { 0, 5, 1, 6, 2, 7 },
+       { 0, 5, 1, 6, 7, 2 },
+       { 0, 5, 6, 1, 2, 7 },
+       { 0, 5, 6, 1, 7, 2 },
+       { 0, 5, 6, 7, 1, 2 }
+  };
+  for (size_t Len = 1; Len < 8; Len++) {
+    std::set<Unit> FoundUnits, ExpectedUnitsWitThisLength;
+    for (int Iter = 0; Iter < 3000; Iter++) {
+      CrossOver(A, B, &C, Len);
+      FoundUnits.insert(C);
+    }
+    for (const Unit &U : Expected)
+      if (U.size() <= Len)
+        ExpectedUnitsWitThisLength.insert(U);
+    EXPECT_EQ(ExpectedUnitsWitThisLength, FoundUnits);
+  }
+}
diff --git a/lib/Fuzzer/test/TestFuzzerCrossOver.cpp b/lib/Fuzzer/test/TestFuzzerCrossOver.cpp
deleted file mode 100644
index 7f7619618ec..00000000000
--- a/lib/Fuzzer/test/TestFuzzerCrossOver.cpp
+++ /dev/null
@@ -1,13 +0,0 @@
-#include "FuzzerInternal.h"
-
-int main() {
-  using namespace fuzzer;
-  Unit A({0, 1, 2, 3, 4}), B({5, 6, 7, 8, 9});
-  Unit C;
-  for (size_t Len = 1; Len < 15; Len++) {
-    for (int Iter = 0; Iter < 1000; Iter++) {
-      CrossOver(A, B, &C, Len);
-      Print(C);
-    }
-  }
-}
diff --git a/lib/Fuzzer/test/unit/lit.cfg b/lib/Fuzzer/test/unit/lit.cfg
new file mode 100644
index 00000000000..0cc31939c55
--- /dev/null
+++ b/lib/Fuzzer/test/unit/lit.cfg
@@ -0,0 +1,7 @@
+import lit.formats
+
+config.name = "LLVMFuzzer-Unittest"
+print config.test_exec_root
+config.test_format = lit.formats.GoogleTest(".", "Unittest")
+config.suffixes = []
+config.test_source_root = config.test_exec_root
diff --git a/lib/Fuzzer/test/unit/lit.site.cfg.in b/lib/Fuzzer/test/unit/lit.site.cfg.in
new file mode 100644
index 00000000000..114daf474b6
--- /dev/null
+++ b/lib/Fuzzer/test/unit/lit.site.cfg.in
@@ -0,0 +1,2 @@
+config.test_exec_root = "@CMAKE_CURRENT_BINARY_DIR@"
+lit_config.load_config(config, "@CMAKE_CURRENT_SOURCE_DIR@/unit/lit.cfg")