Index: cfe/trunk/utils/perf-training/CMakeLists.txt
===================================================================
--- cfe/trunk/utils/perf-training/CMakeLists.txt
+++ cfe/trunk/utils/perf-training/CMakeLists.txt
@@ -30,13 +30,13 @@
   endif()
 
   if(NOT LLVM_PROFDATA)
-    message(FATAL_ERROR "Must set LLVM_PROFDATA to point to llvm-profdata to use for merging PGO data")
+    message(STATUS "To enable merging PGO data LLVM_PROFDATA has to point to llvm-profdata")
+  else()
+    add_custom_target(generate-profdata
+      COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py merge ${LLVM_PROFDATA} ${CMAKE_CURRENT_BINARY_DIR}/clang.profdata ${CMAKE_CURRENT_BINARY_DIR}
+      COMMENT "Merging profdata"
+      DEPENDS generate-profraw)
   endif()
-
-  add_custom_target(generate-profdata
-    COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py merge ${LLVM_PROFDATA} ${CMAKE_CURRENT_BINARY_DIR}/clang.profdata ${CMAKE_CURRENT_BINARY_DIR}
-    COMMENT "Merging profdata"
-    DEPENDS generate-profraw)
 endif()
 
 find_program(DTRACE dtrace)