diff --git a/test/Makefile b/test/Makefile
index 67644ce..391776b 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -32,6 +32,10 @@
 RUNTESTFLAGS += --tool $(CLEANED_TESTSUITE)
 endif
 
+ifdef VG
+VALGRIND := valgrind --tool=memcheck --quiet --trace-children=yes --error-exitcode=3 --leak-check=full
+endif
+
 IGNORE_TESTS :=
 
 ifndef RUNLLVM2CPP
@@ -77,7 +81,9 @@
 clean::
 	$(RM) -rf `find $(LLVM_OBJ_ROOT)/test -name Output -type d -print`
 
-site.exp: Makefile $(LLVM_OBJ_ROOT)/Makefile.config
+FORCE:
+
+site.exp: FORCE
 	@echo 'Making a new site.exp file...'
 	@echo '## these variables are automatically generated by make ##' >site.tmp
 	@echo '# Do not edit here.  If you wish to override these values' >>site.tmp
@@ -103,6 +109,7 @@
 	@echo 'set llvmgccmajvers "$(LLVMGCC_MAJVERS)"' >> site.tmp
 	@echo 'set shlibext "$(SHLIBEXT)"' >> site.tmp
 	@echo 'set ocamlc "$(OCAMLC) -cc $(CXX) -I $(LibDir)/ocaml"' >> site.tmp
+	@echo 'set valgrind "$(VALGRIND)"' >> site.tmp
 	@echo '## All variables above are generated by configure. Do Not Edit ## ' >>site.tmp
 	@test ! -f site.exp || \
 	sed '1,/^## All variables above are.*##/ d' site.exp >> site.tmp
diff --git a/test/lib/llvm.exp b/test/lib/llvm.exp
index 3d7588d..a844152 100644
--- a/test/lib/llvm.exp
+++ b/test/lib/llvm.exp
@@ -49,11 +49,14 @@
   global srcroot objroot srcdir objdir subdir target_triplet prcontext 
   global llvmgcc llvmgxx llvmgcc_version llvmgccmajvers ocamlc
   global gccpath gxxpath compile_c compile_cxx link shlibext llvmlibsdir
+  global valgrind
   set path [file join $srcdir $subdir]
 
   # Substitute all Tcl variables.
   set new_line [subst $line ]
 
+  #replace %% with _#MARKER#_ to make the replacement of %% more predictable
+  regsub -all {%%} $new_line {_#MARKER#_} new_line
   #replace %prcontext with prcontext.tcl (Must replace before %p)
   regsub -all {%prcontext} $new_line $prcontext new_line
   #replace %llvmgcc with actual path to llvmgcc
@@ -78,8 +81,28 @@
   regsub -all {%s} $new_line $test new_line
   #replace %t with temp filenames
   regsub -all {%t} $new_line $tmpFile new_line
-  #replace %% with %
-  regsub -all {%%} $new_line % new_line
+  #replace _#MARKER#_ with %
+  regsub -all {_#MARKER#_} $new_line % new_line
+
+  #valgind related stuff
+# regsub -all {bugpoint } $new_line "$valgrind bugpoint " new_line
+  regsub -all {llc } $new_line "$valgrind llc " new_line
+  regsub -all {lli } $new_line "$valgrind lli " new_line
+  regsub -all {llvm-ar } $new_line "$valgrind llvm-ar " new_line
+  regsub -all {llvm-as } $new_line "$valgrind llvm-as " new_line
+  regsub -all {llvm-bcanalyzer } $new_line "$valgrind llvm-bcanalyzer " new_line
+  regsub -all {llvm-dis } $new_line "$valgrind llvm-dis " new_line
+  regsub -all {llvm-extract } $new_line "$valgrind llvm-extract " new_line
+  regsub -all {llvm-ld } $new_line "$valgrind llvm-ld " new_line
+  regsub -all {llvm-link } $new_line "$valgrind llvm-link " new_line
+  regsub -all {llvm-nm } $new_line "$valgrind llvm-nm " new_line
+  regsub -all {llvm-prof } $new_line "$valgrind llvm-prof " new_line
+  regsub -all {llvm-ranlib } $new_line "$valgrind llvm-ranlib " new_line
+  regsub -all {([^a-zA-Z_-])opt } $new_line "\\1$valgrind opt " new_line
+  regsub -all {^opt } $new_line "$valgrind opt " new_line
+  regsub -all {tblgen } $new_line "$valgrind tblgen " new_line
+  regsub -all "not $valgrind " $new_line "$valgrind not " new_line
+
   return $new_line
 }