diff --git a/configure b/configure
index 8604dfeaffc..05bfdb3e9fd 100755
--- a/configure
+++ b/configure
@@ -411,6 +411,7 @@ VAL_OPTIONS=""
 
 opt valgrind 0 "run tests with valgrind (memcheck by default)"
 opt helgrind 0 "run tests with helgrind instead of memcheck"
+opt valgrind-rpass 1 "run rpass-valgrind tests with valgrind"
 opt docs     1 "build documentation"
 opt optimize 1 "build optimized rust code"
 opt optimize-cxx 1 "build optimized C++ code"
@@ -1236,15 +1237,6 @@ then
     putvar CFG_PANDOC
 fi
 
-# Valgrind is only reliable on Linux. On Windows it doesn't work at all, and
-# on the Mac the dynamic linker causes Valgrind to emit a huge stream of
-# errors.
-if [ $CFG_OSTYPE != unknown-linux-gnu ] && [ $CFG_OSTYPE != apple-darwin ]
-then
-    CFG_BAD_VALGRIND=1
-    putvar CFG_BAD_VALGRIND
-fi
-
 putvar CFG_LLVM_ROOT
 putvar CFG_LLVM_SRC_DIR
 
diff --git a/mk/main.mk b/mk/main.mk
index 93fdda869c9..e927f6ad468 100644
--- a/mk/main.mk
+++ b/mk/main.mk
@@ -174,19 +174,20 @@ else
   CFG_VALGRIND_COMPILE :=
 endif
 
-VALGRIND_PATH :=$(CFG_VALGRIND)
+
+ifndef CFG_DISABLE_VALGRIND_RPASS
+  $(info cfg: enabling valgrind run-pass tests (CFG_ENABLE_VALGRIND_RPASS))
+  CFG_VALGRIND_RPASS :=$(CFG_VALGRIND)
+else
+  CFG_VALGRIND_RPASS :=
+endif
+
 
 ifdef CFG_ENABLE_VALGRIND
   $(info cfg: enabling valgrind (CFG_ENABLE_VALGRIND))
 else
   CFG_VALGRIND :=
 endif
-ifdef CFG_BAD_VALGRIND
-  $(info cfg: disabling valgrind due to its unreliability on this platform)
-  CFG_VALGRIND :=
-  VALGRIND_PATH :=
-endif
-
 
 ######################################################################
 # Target-and-rule "utility variables"
diff --git a/mk/platform.mk b/mk/platform.mk
index beefefcf5e5..9db9138d5e9 100644
--- a/mk/platform.mk
+++ b/mk/platform.mk
@@ -58,6 +58,20 @@ ifdef CFG_VALGRIND
   endif
 endif
 
+# If we actually want to run Valgrind on a given platform, set this variable
+define DEF_GOOD_VALGRIND
+  ifeq ($(OSTYPE_$(1)),unknown-linux-gnu)
+    GOOD_VALGRIND_$(1) = 1
+  endif
+  ifneq (,$(filter $(OSTYPE_$(1)),darwin freebsd))
+    ifeq (HOST_$(1),x86_64)
+      GOOD_VALGRIND_$(1) = 1
+    endif
+  endif
+endef
+$(foreach t,$(CFG_TARGET),$(eval $(call DEF_GOOD_VALGRIND,$(t))))
+$(foreach t,$(CFG_TARGET),$(info cfg: good valgrind for $(t) is $(GOOD_VALGRIND_$(t))))
+
 ifneq ($(findstring linux,$(CFG_OSTYPE)),)
   ifdef CFG_PERF
     ifneq ($(CFG_PERF_WITH_LOGFD),)
diff --git a/mk/tests.mk b/mk/tests.mk
index 07e13057e36..3bbd871e5be 100644
--- a/mk/tests.mk
+++ b/mk/tests.mk
@@ -530,9 +530,6 @@ CTEST_SRC_BASE_rpass-valgrind = run-pass-valgrind
 CTEST_BUILD_BASE_rpass-valgrind = run-pass-valgrind
 CTEST_MODE_rpass-valgrind = run-pass-valgrind
 CTEST_RUNTOOL_rpass-valgrind = $(CTEST_RUNTOOL)
-ifdef VALGRIND_PATH
-CTEST_TESTARGS += --valgrind-path "$(VALGRIND_PATH)"
-endif
 
 CTEST_SRC_BASE_rpass-full = run-pass-fulldeps
 CTEST_BUILD_BASE_rpass-full = run-pass-fulldeps
@@ -662,6 +659,19 @@ CTEST_COMMON_ARGS$(1)-T-$(2)-H-$(3) := \
         --target-rustcflags "$(RUSTC_FLAGS_$(2)) $$(CTEST_RUSTC_FLAGS) -L $$(RT_OUTPUT_DIR_$(2))" \
         $$(CTEST_TESTARGS)
 
+ifdef CFG_VALGRIND_RPASS
+ifdef GOOD_VALGRIND_$(2)
+$(info cfg: valgrind-path set to $(CFG_VALGRIND_RPASS))
+CTEST_COMMON_ARGS$(1)-T-$(2)-H-$(3) += --valgrind-path "$(CFG_VALGRIND_RPASS)"
+endif
+endif
+
+ifndef CFG_DISABLE_VALGRIND_RPASS
+ifdef GOOD_VALGRIND_$(2)
+CTEST_COMMON_ARGS$(1)-T-$(2)-H-$(3) += --force-valgrind
+endif
+endif
+
 CTEST_DEPS_rpass_$(1)-T-$(2)-H-$(3) = $$(RPASS_TESTS)
 CTEST_DEPS_rpass-valgrind_$(1)-T-$(2)-H-$(3) = $$(RPASS_VALGRIND_TESTS)
 CTEST_DEPS_rpass-full_$(1)-T-$(2)-H-$(3) = $$(RPASS_FULL_TESTS) $$(CSREQ$(1)_T_$(3)_H_$(3)) $$(SREQ$(1)_T_$(2)_H_$(3))
diff --git a/src/compiletest/common.rs b/src/compiletest/common.rs
index d8a0afc38e7..2c917f7aefe 100644
--- a/src/compiletest/common.rs
+++ b/src/compiletest/common.rs
@@ -76,6 +76,10 @@ pub struct Config {
     // The valgrind path
     pub valgrind_path: Option<String>,
 
+    // Whether to fail if we can't run run-pass-valgrind tests under valgrind
+    // (or, alternatively, to silently run them like regular run-pass tests).
+    pub force_valgrind: bool,
+
     // The directory containing the tests to run
     pub src_base: Path,
 
diff --git a/src/compiletest/compiletest.rs b/src/compiletest/compiletest.rs
index 3ac25937b38..7af25de1f6f 100644
--- a/src/compiletest/compiletest.rs
+++ b/src/compiletest/compiletest.rs
@@ -39,6 +39,11 @@ pub mod errors;
 pub fn main() {
     let args = os::args();
     let config = parse_config(args);
+
+    if config.valgrind_path.is_none() && config.force_valgrind {
+        fail!("Can't find Valgrind to run Valgrind tests");
+    }
+
     log_config(&config);
     run_tests(&config);
 }
@@ -50,7 +55,8 @@ pub fn parse_config(args: Vec<String> ) -> Config {
           reqopt("", "run-lib-path", "path to target shared libraries", "PATH"),
           reqopt("", "rustc-path", "path to rustc to use for compiling", "PATH"),
           optopt("", "clang-path", "path to  executable for codegen tests", "PATH"),
-          optopt("", "valgrind-path", "path to valgrind executable for valgrind tests", "PROGRAM"),
+          optopt("", "valgrind-path", "path to Valgrind executable for Valgrind tests", "PROGRAM"),
+          optflag("", "force-valgrind", "fail if Valgrind tests cannot be run under Valgrind"),
           optopt("", "llvm-bin-path", "path to directory holding llvm binaries", "DIR"),
           reqopt("", "src-base", "directory to scan for test files", "PATH"),
           reqopt("", "build-base", "directory to deposit test outputs", "PATH"),
@@ -127,6 +133,7 @@ pub fn parse_config(args: Vec<String> ) -> Config {
         rustc_path: opt_path(matches, "rustc-path"),
         clang_path: matches.opt_str("clang-path").map(|s| Path::new(s)),
         valgrind_path: matches.opt_str("valgrind-path"),
+        force_valgrind: matches.opt_present("force-valgrind"),
         llvm_bin_path: matches.opt_str("llvm-bin-path").map(|s| Path::new(s)),
         src_base: opt_path(matches, "src-base"),
         build_base: opt_path(matches, "build-base"),
@@ -164,7 +171,7 @@ pub fn parse_config(args: Vec<String> ) -> Config {
             !opt_str2(matches.opt_str("adb-test-dir")).is_empty(),
         lldb_python_dir: matches.opt_str("lldb-python-dir"),
         test_shard: test::opt_shard(matches.opt_str("test-shard")),
-        verbose: matches.opt_present("verbose")
+        verbose: matches.opt_present("verbose"),
     }
 }
 
diff --git a/src/compiletest/runtest.rs b/src/compiletest/runtest.rs
index 6b542fed68d..34129dedbd8 100644
--- a/src/compiletest/runtest.rs
+++ b/src/compiletest/runtest.rs
@@ -166,6 +166,7 @@ fn run_rpass_test(config: &Config, props: &TestProps, testfile: &Path) {
 
 fn run_valgrind_test(config: &Config, props: &TestProps, testfile: &Path) {
     if config.valgrind_path.is_none() {
+        assert!(!config.force_valgrind);
         return run_rpass_test(config, props, testfile);
     }
 
@@ -175,7 +176,6 @@ fn run_valgrind_test(config: &Config, props: &TestProps, testfile: &Path) {
         fatal_proc_rec("compilation failed!", &proc_res);
     }
 
-    println!("running valgrind");
     let mut new_config = config.clone();
     new_config.runtool = new_config.valgrind_path.clone();
     proc_res = exec_compiled_test(&new_config, props, testfile);