diff --git a/mk/platform.mk b/mk/platform.mk
index 9bfae5e9691..0dbefc3518c 100644
--- a/mk/platform.mk
+++ b/mk/platform.mk
@@ -105,10 +105,9 @@ ifdef CFG_UNIXY
   CFG_PATH_MUNGE := true
   CFG_EXE_SUFFIX :=
   CFG_LDPATH :=
-  CFG_RUN=$(CFG_LDENV)=$(1) $(2)
-  CFG_RUN_TARG=$(call CFG_RUN,$(CFG_BUILD_DIR)/$(HOST_LIB$(1)),$(2))
-  CFG_RUN_TEST=$(call CFG_RUN,$(call CFG_TESTLIB,$(1)),\
-      $(CFG_VALGRIND) $(1))
+  CFG_RUN=$(2)
+  CFG_RUN_TARG=$(call CFG_RUN,,$(2))
+  CFG_RUN_TEST=$(call CFG_RUN,,$(CFG_VALGRIND) $(1))
   CFG_LIBUV_LINK_FLAGS=-lpthread
 
   ifdef CFG_ENABLE_MINGW_CROSS
diff --git a/src/compiletest/procsrv.rs b/src/compiletest/procsrv.rs
index 6a40aaccaf4..1563e3112ca 100644
--- a/src/compiletest/procsrv.rs
+++ b/src/compiletest/procsrv.rs
@@ -131,7 +131,7 @@ fn worker(p: port<request>) {
         let spawnproc =
             bind run::spawn_process(execparms.prog, execparms.args,
                                     pipe_in.in, pipe_out.out, pipe_err.out);
-        let pid = with_lib_path(execparms.lib_path, spawnproc);
+        let pid = maybe_with_lib_path(execparms.lib_path, spawnproc);
 
         os::libc::close(pipe_in.in);
         os::libc::close(pipe_out.out);
@@ -151,6 +151,18 @@ fn worker(p: port<request>) {
     }
 }
 
+// Only windows needs to set the library path
+#[cfg(target_os = "win32")]
+fn maybe_with_lib_path<@T>(path: str, f: fn() -> T) -> T {
+    with_lib_path(path, f)
+}
+
+#[cfg(target_os = "linux")]
+#[cfg(target_os = "macos")]
+fn maybe_with_lib_path<@T>(_path: str, f: fn() -> T) -> T {
+    f()
+}
+
 fn with_lib_path<@T>(path: str, f: fn() -> T) -> T {
     let maybe_oldpath = getenv(util::lib_path_env_var());
     append_lib_path(path);
diff --git a/src/compiletest/runtest.rs b/src/compiletest/runtest.rs
index de188f3927e..ebedb4f0685 100644
--- a/src/compiletest/runtest.rs
+++ b/src/compiletest/runtest.rs
@@ -310,6 +310,14 @@ fn program_output(cx: cx, testfile: str, lib_path: str, prog: str,
          cmdline: cmdline};
 }
 
+// Linux and mac don't require adjusting the library search path
+#[cfg(target_os = "linux")]
+#[cfg(target_os = "macos")]
+fn make_cmdline(_libpath: str, prog: str, args: [str]) -> str {
+    #fmt["%s %s", prog, str::connect(args, " ")]
+}
+
+#[cfg(target_os = "win32")]
 fn make_cmdline(libpath: str, prog: str, args: [str]) -> str {
     #fmt["%s %s %s", lib_path_cmd_prefix(libpath), prog,
          str::connect(args, " ")]