diff --git a/doc/NEWS.Rd b/doc/NEWS.Rd
index 75ce6d184f0..3ca8f9bc260 100644
--- a/doc/NEWS.Rd
+++ b/doc/NEWS.Rd
@@ -87,6 +87,10 @@
 
       \item The set operations now avoid the \code{as.vector()}
       transformation for same-kind apparently vector-like operands.
+
+      \item \code{md5sum()} can be used to compute an MD5 hash of a raw
+      vector of bytes by using the \code{bytes=} argument instead
+      of \code{files=}. The two arguments are mutually exclusive.
     }
   }
 
diff --git a/src/library/tools/R/md5.R b/src/library/tools/R/md5.R
index 22e27127505..efe4d052984 100644
--- a/src/library/tools/R/md5.R
+++ b/src/library/tools/R/md5.R
@@ -16,9 +16,16 @@
 #  A copy of the GNU General Public License is available at
 #  https://www.R-project.org/Licenses/
 
-md5sum <- function(files) {
-    files <- path.expand(files)
-    structure(.Call(C_Rmd5, files), names=files)
+md5sum <- function(files, bytes) {
+    if (!missing(files) && !missing(bytes))
+        stop("files and bytes are mutually exclusive")
+    if (!missing(bytes)) {
+        if (!is.raw(bytes)) stop("bytes must be a raw vector")
+        .Call(C_Rmd5, bytes)
+    } else {
+        files <- path.expand(files)
+        structure(.Call(C_Rmd5, files), names=files)
+    }
 }
 
 .installMD5sums <- function(pkgDir, outDir = pkgDir)
diff --git a/src/library/tools/man/md5sum.Rd b/src/library/tools/man/md5sum.Rd
index 9136ac30f96..437e45a0f77 100644
--- a/src/library/tools/man/md5sum.Rd
+++ b/src/library/tools/man/md5sum.Rd
@@ -7,13 +7,15 @@
 \alias{md5sum}
 \title{Compute MD5 Checksums}
 \description{
-  Compute the 32-byte MD5 hashes of one or more files.
+  Compute the 32-byte MD5 hashes of one or more files, or a raw vector of bytes.
 }
 \usage{
-md5sum(files)
+md5sum(files, bytes)
 }
 \arguments{
   \item{files}{character. The paths of file(s) whose contents are to be hashed.}
+  \item{bytes}{raw. Bytes to be hashed.
+    NB: \code{bytes} and \code{files} are mutually exclusive.}
 }
 \details{
   A MD5 \sQuote{hash} or \sQuote{checksum} or \sQuote{message digest} is
@@ -34,6 +36,8 @@ md5sum(files)
   equal to \code{files} (possibly expanded).  The elements will be
   \code{NA} for non-existent or unreadable files, otherwise a
   32-character string of hexadecimal digits.
+  
+  For \code{bytes} the result is a single 32-character string.
 }
 \source{
   The underlying C code was written by \I{Ulrich Drepper} and extracted from
@@ -44,6 +48,8 @@ md5sum(files)
 }
 \examples{
 as.vector(md5sum(dir(R.home(), pattern = "^COPY", full.names = TRUE)))
+md5sum(bytes=raw())
+md5sum(bytes=charToRaw("abc"))
 }
 \keyword{utilities}
 
diff --git a/src/library/tools/src/Rmd5.c b/src/library/tools/src/Rmd5.c
index a3cffd45207..fd4afe5996e 100644
--- a/src/library/tools/src/Rmd5.c
+++ b/src/library/tools/src/Rmd5.c
@@ -44,6 +44,16 @@ SEXP Rmd5(SEXP files)
     FILE *fp;
     unsigned char resblock[16];
 
+    /* RAW mode: hash of one buffer instead of files */
+    if (TYPEOF(files) == RAWSXP) {
+	/* there is really no failure possible, but just in case... */
+	if (!md5_buffer(RAW(files), XLENGTH(files), resblock))
+	    return ScalarString(NA_STRING);
+	for(j = 0; j < 16; j++)
+	    snprintf (out+2*j, 33-2*j, "%02x", resblock[j]);
+	return mkString(out);
+    }
+    /* otherwise list of files */
     if(!isString(files)) error(_("argument 'files' must be character"));
     PROTECT(ans = allocVector(STRSXP, nfiles));
     for(i = 0; i < nfiles; i++) {
diff --git a/src/library/tools/src/md5.c b/src/library/tools/src/md5.c
index f1e0c90f4c9..22a1b0e4efc 100644
--- a/src/library/tools/src/md5.c
+++ b/src/library/tools/src/md5.c
@@ -163,12 +163,11 @@ md5_stream (FILE *stream, void *resblock)
   return 0;
 }
 
-#ifdef UNUSED
 /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
    result is always in little endian byte order, so that a byte-wise
    output yields to the wanted ASCII representation of the message
    digest.  */
-static void *
+void *
 md5_buffer (const char *buffer, size_t len, void *resblock)
 {
   struct md5_ctx ctx;
@@ -182,7 +181,6 @@ md5_buffer (const char *buffer, size_t len, void *resblock)
   /* Put result in desired memory area.  */
   return md5_finish_ctx (&ctx, resblock);
 }
-#endif
 
 static void
  md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
diff --git a/src/library/tools/src/md5.h b/src/library/tools/src/md5.h
index 82fa4b45ace..3b1becfe486 100644
--- a/src/library/tools/src/md5.h
+++ b/src/library/tools/src/md5.h
@@ -100,6 +100,8 @@ struct md5_ctx
    resulting message digest number will be written into the 16 bytes
    beginning at RESBLOCK.  */
 extern int md5_stream __P ((FILE *stream, void *resblock));
+/* same as above for a buffer instead of file; returns resblock on success */
+extern void* md5_buffer __P ((const char *buffer, size_t len, void *resblock));
 
 #ifndef ROL_UNUSED
 /* The following is from gnupg-1.0.2's cipher/bithelp.h.  */
diff --git a/tests/Examples/tools-Ex.Rout.save b/tests/Examples/tools-Ex.Rout.save
index cf5bb12e653..696a472562d 100644
--- a/tests/Examples/tools-Ex.Rout.save
+++ b/tests/Examples/tools-Ex.Rout.save
@@ -796,6 +796,10 @@ character(0)
 > 
 > as.vector(md5sum(dir(R.home(), pattern = "^COPY", full.names = TRUE)))
 [1] "eb723b61539feef013de476e68b5c50a"
+> md5sum(bytes=raw())
+[1] "d41d8cd98f00b204e9800998ecf8427e"
+> md5sum(bytes=charToRaw("abc"))
+[1] "900150983cd24fb0d6963f7d28e17f72"
 > 
 > 
 >