Index: MultiSource/Applications/Burg/CMakeLists.txt
===================================================================
--- MultiSource/Applications/Burg/CMakeLists.txt
+++ MultiSource/Applications/Burg/CMakeLists.txt
@@ -14,7 +14,11 @@
 set(Source ${ExtraSource} ${TMP1})
 
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
-add_yacc_parser(burg_parser gram.y ${CMAKE_CURRENT_BINARY_DIR}/y.tab.c ${CMAKE_CURRENT_BINARY_DIR}/y.tab.h)
-    llvm_multisource()
+
+# Only build Burg if yacc is installed.
+if(YACC_EXECUTABLE)
+  add_yacc_parser(burg_parser gram.y ${CMAKE_CURRENT_BINARY_DIR}/y.tab.c ${CMAKE_CURRENT_BINARY_DIR}/y.tab.h)
+  llvm_multisource()
+endif(YACC_EXECUTABLE)
 
 llvm_add_subdirectories(${DIRS} ${PARALLEL_DIRS})