-PARALLEL_DIRS := llvm-as llvm-dis opt gccas llc llvm-link lli gccld llvm-stub \
- analyze extract llvm-nm llvm-prof llvm-ar llvm-ranlib \
- llvm-bcanalyzer llvmc llvm-ld
-
-# The bugpoint and llvm-db tools are not portable to Win32 because they depend
-# on fork(2) behavior that Win32 doesn't have. At some point they'll be
-# rewritten to not depend on fork at which time they should be added back to
-# the list above.
-ifneq($(OS),Win32)
-PARALLEL_DIRS += bugpoint llvm-db
+
+# Build clang if present.
+OPTIONAL_PARALLEL_DIRS := clang
+
+# NOTE: The tools are organized into five groups of four consisting of one
+# large and three small executables. This is done to minimize memory load
+# in parallel builds. Please retain this ordering.
+
+# libEnhancedDisassembly must be built ahead of llvm-mc
+# because llvm-mc links against libEnhancedDisassembly
+DIRS := llvm-config edis llvm-mc
+PARALLEL_DIRS := opt llvm-as llvm-dis \
+ llc llvm-ranlib llvm-ar llvm-nm \
+ llvm-ld llvm-prof llvm-link \
+ lli llvm-extract \
+ bugpoint llvm-bcanalyzer llvm-stub \
+ llvmc
+
+# Let users override the set of tools to build from the command line.
+ifdef ONLY_TOOLS
+ OPTIONAL_PARALLEL_DIRS :=
+ PARALLEL_DIRS := $(ONLY_TOOLS)