diff --git a/exec/hgmain/Cargo.toml b/exec/hgmain/Cargo.toml
index 3b4aa7eb17..ddffa5552f 100644
--- a/exec/hgmain/Cargo.toml
+++ b/exec/hgmain/Cargo.toml
@@ -14,6 +14,7 @@ path = "../../lib/encoding"
 path = "../../lib/hgpython"
 
 [features]
+buildinfo = []
 default = []
 with_chg = []
 hgdev = ["hgpython/hgdev"]
diff --git a/exec/hgmain/build.rs b/exec/hgmain/build.rs
index 4ba09c21b8..2ea3566f4c 100644
--- a/exec/hgmain/build.rs
+++ b/exec/hgmain/build.rs
@@ -14,6 +14,11 @@ fn main() {
                 "cargo:rerun-if-changed={}",
                 lib_dir.join("libchg.a").display()
             );
+            #[cfg(feature = "buildinfo")]
+            println!(
+                "cargo:rerun-if-changed={}",
+                lib_dir.join("buildinfo.a").display()
+            );
         }
     }
 }
diff --git a/exec/hgmain/src/buildinfo.rs b/exec/hgmain/src/buildinfo.rs
new file mode 100644
index 0000000000..3a7da4e2c8
--- /dev/null
+++ b/exec/hgmain/src/buildinfo.rs
@@ -0,0 +1,7 @@
+// Copyright Facebook, Inc. 2019
+
+#[cfg(feature = "buildinfo")]
+#[link(name = "buildinfo", kind = "static")]
+extern "C" {
+    pub fn print_buildinfo();
+}
diff --git a/exec/hgmain/src/main.rs b/exec/hgmain/src/main.rs
index 2344509adc..813a4cba8a 100644
--- a/exec/hgmain/src/main.rs
+++ b/exec/hgmain/src/main.rs
@@ -1,4 +1,5 @@
 // Copyright Facebook, Inc. 2018
+
 #[cfg(feature = "with_chg")]
 extern crate dirs;
 extern crate encoding;
@@ -7,6 +8,7 @@ extern crate hgpython;
 extern crate libc;
 use hgpython::HgPython;
 
+mod buildinfo;
 #[cfg(feature = "with_chg")]
 mod chg;
 #[cfg(feature = "with_chg")]
@@ -23,6 +25,20 @@ fn call_embedded_python() {
 }
 
 fn main() {
+    #[cfg(feature = "buildinfo")]
+    {
+        // This code path keeps buildinfo-related symbols alive.
+        use std::env;
+        if let Some(arg0) = env::args().nth(0) {
+            if arg0.ends_with("buildinfo") {
+                unsafe {
+                    buildinfo::print_buildinfo();
+                }
+                return;
+            }
+        }
+    }
+
     #[cfg(feature = "with_chg")]
     maybe_call_chg();
     call_embedded_python();
diff --git a/setup.py b/setup.py
index 6f2c92a515..a302ba7855 100644
--- a/setup.py
+++ b/setup.py
@@ -18,6 +18,7 @@ import os
 import py_compile
 import re
 import shutil
+import socket
 import stat
 import struct
 import subprocess
@@ -452,15 +453,24 @@ def localhgenv():
     return env
 
 
-def pickversion():
-    hg = findhg()
+hg = findhg()
+
+
+def hgtemplate(template, cast=None):
     if not hg:
-        # if hg is not found, fallback to a fixed version
-        return "4.4.2"
+        return None
+    result = sysstr(hg.run(["log", "-r.", "-T", template]))
+    if result and cast:
+        result = cast(result)
+    return result
+
+
+def pickversion():
     # New version system: YYMMDD_HHmmSS_hash
     # This is duplicated a bit from build_rpm.py:auto_release_str()
     template = '{sub("([:+-]|\d\d\d\d$)", "",date|isodatesec)} {node|short}'
-    out = sysstr(hg.run(["log", "-r.", "-T", template]))
+    # if hg is not found, fallback to a fixed version
+    out = hgtemplate(template) or ""
     # Some tools parse this number to figure out if they support this version of
     # Mercurial, so prepend with 4.4.2.
     # ex. 4.4.2_20180105_214829_58fda95a0202
@@ -502,6 +512,77 @@ if not os.path.isdir(builddir):
         ensureexists(builddir)
 
 
+def writebuildinfoc():
+    """Write build/buildinfo.c"""
+    commithash = hgtemplate("{node}")
+    commitunixtime = hgtemplate('{sub("[^0-9].*","",date)}', cast=int)
+
+    # Search 'extractBuildInfoFromELF' in fbcode for supported fields.
+    buildinfo = {
+        "Host": socket.gethostname(),
+        "PackageName": os.environ.get("RPM_PACKAGE_NAME")
+        or os.environ.get("PACKAGE_NAME"),
+        "PackageRelease": os.environ.get("RPM_PACKAGE_RELEASE")
+        or os.environ.get("PACKAGE_RELEASE"),
+        "PackageVersion": os.environ.get("RPM_PACKAGE_VERSION")
+        or os.environ.get("PACKAGE_VERSION"),
+        "Path": os.getcwd(),
+        "Platform": os.environ.get("RPM_OS"),
+        "Revision": commithash,
+        "RevisionCommitTimeUnix": commitunixtime,
+        "TimeUnix": int(time.time()),
+        "UpstreamRevision": commithash,
+        "UpstreamRevisionCommitTimeUnix": commitunixtime,
+        "User": os.environ.get("USER"),
+    }
+
+    buildinfosrc = """
+#include <stdio.h>
+#include <time.h>
+"""
+    for name, value in sorted(buildinfo.items()):
+        if isinstance(value, str):
+            buildinfosrc += 'const char *BuildInfo_k%s = "%s";\n' % (
+                name,
+                value.replace('"', '\\"'),
+            )
+        elif isinstance(value, int):
+            # The only usage of int is timestamp
+            buildinfosrc += "const time_t BuildInfo_k%s = %d;\n" % (name, value)
+
+    buildinfosrc += """
+/* This function keeps references of the symbols and prevents them from being
+ * optimized out if this function is used. */
+void print_buildinfo() {
+"""
+    for name, value in sorted(buildinfo.items()):
+        if isinstance(value, str):
+            buildinfosrc += (
+                '  fprintf(stderr, "%(name)s: %%s (at %%p)\\n", BuildInfo_k%(name)s, BuildInfo_k%(name)s);\n'
+                % {"name": name}
+            )
+        elif isinstance(value, int):
+            buildinfosrc += (
+                '  fprintf(stderr, "%(name)s: %%lu (at %%p)\\n", (long unsigned)BuildInfo_k%(name)s, &BuildInfo_k%(name)s) ;\n'
+                % {"name": name}
+            )
+    buildinfosrc += """
+}
+"""
+
+    path = pjoin(builddir, "buildinfo.c")
+    write_if_changed(path, buildinfosrc)
+    return path
+
+
+# If NEED_BUILDINFO is set, write buildinfo.
+# For rpmbuild, imply NEED_BUILDINFO.
+needbuildinfo = bool(os.environ.get("NEED_BUILDINFO", "RPM_PACKAGE_NAME" in os.environ))
+
+if needbuildinfo:
+    buildinfocpath = writebuildinfoc()
+
+
 try:
     oldpolicy = os.environ.get("HGMODULEPOLICY", None)
     os.environ["HGMODULEPOLICY"] = "py"
@@ -1833,6 +1914,16 @@ libraries = [
         },
     ),
 ]
+if needbuildinfo:
+    libraries += [
+        (
+            "buildinfo",
+            {
+                "sources": [buildinfocpath],
+                "extra_args": filter(None, cflags + [WALL, PIC]),
+            },
+        )
+    ]
 
 if not iswindows:
     libraries.append(
@@ -2104,6 +2195,7 @@ hgmainfeatures = (
         filter(
             None,
             [
+                "buildinfo" if needbuildinfo else None,
                 "hgdev" if os.environ.get("HGDEV") else None,
                 "with_chg" if not iswindows else None,
             ],