diff --git a/Makefile.in b/Makefile.in
index 3daf9e8dbe1..c32ac1e4986 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -35,6 +35,14 @@ CFG_RUNTIME :=$(call CFG_LIB_NAME,rustrt)
 CFG_RUSTLLVM :=$(call CFG_LIB_NAME,rustllvm)
 CFG_STDLIB :=$(call CFG_LIB_NAME,std)
 
+# version-string calculation
+CFG_GIT_DIR := $(CFG_SRC_DIR).git
+CFG_VERSION := prerelease
+ifneq ($(wildcard $(CFG_GIT_DIR)),)
+    CFG_VERSION += $(shell git --git-dir=$(CFG_GIT_DIR) log -1 \
+                     --pretty=format:'(%h %ci)')
+endif
+
 ifdef CFG_OCAMLC_OPT
   $(info cfg: have ocaml native compiler)
   OPT=.opt
@@ -140,6 +148,7 @@ SREQ2 := stage2/rustc$(X) $(LREQ) stage3/glue.o stage3/$(CFG_STDLIB)
 ######################################################################
 
 export CFG_SRC_DIR
+export CFG_VERSION
 
 ######################################################################
 # Subprograms
diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index b7bca48a068..aef6ef3bdcd 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -127,11 +127,12 @@ fn pretty_print_input(session.session sess,
 }
 
 fn version(str argv0) {
-    auto git_rev = ""; // when snapshotted to extenv: #env("GIT_REV");
-    if (_str.byte_len(git_rev) != 0u) {
-        git_rev = #fmt(" (git: %s)", git_rev);
+    auto vers = "unknown version";
+    auto env_vers = #env("CFG_VERSION");
+    if (_str.byte_len(env_vers) != 0u) {
+        vers = env_vers;
     }
-    io.stdout().write_str(#fmt("%s prerelease%s\n", argv0, git_rev));
+    io.stdout().write_str(#fmt("%s %s\n", argv0, vers));
 }
 
 fn usage(str argv0) {