diff --git a/massif/ms_main.c b/massif/ms_main.c
index 103d27e8c..76b43d9d9 100644
--- a/massif/ms_main.c
+++ b/massif/ms_main.c
@@ -326,8 +326,8 @@ static SizeT peak_snapshot_total_szB = 0;
 // memory.  An alternative to milliseconds as a unit of program "time".
 static ULong total_allocs_deallocs_szB = 0;
 
-// Current directory at startup.
-static Char base_dir[VKI_PATH_MAX]; // XXX: currently unused
+// The output file name.  Controlled by --massif-out-file.
+static Char* massif_out_file = NULL;
 
 // We don't start taking snapshots until the first basic block is executed,
 // rather than doing it in ms_post_clo_init (which is the obvious spot), for
@@ -420,6 +420,7 @@ static double clo_peak_inaccuracy = 1.0;  // percentage
 static UInt   clo_time_unit       = TimeMS;
 static UInt   clo_detailed_freq   = 10;
 static UInt   clo_max_snapshots   = 100;
+static Char*  clo_massif_out_file = "massif.out.%p";
 
 static XArray* args_for_massif;
 
@@ -450,6 +451,10 @@ static Bool ms_process_cmd_line_option(Char* arg)
       VG_(addToXA)(alloc_fns, &alloc_fn);
    }
 
+   else if (VG_CLO_STREQN(14, arg, "--massif-out-file=")) {
+      clo_massif_out_file = &arg[18];
+   }
+
    else
       return VG_(replacement_malloc_process_cmd_line_option)(arg);
 
@@ -471,6 +476,7 @@ static void ms_print_usage(void)
 "                               alloc'd/dealloc'd on the heap [ms]\n"
 "    --detailed-freq=<N>       every Nth snapshot should be detailed [10]\n"
 "    --max-snapshots=<N>       maximum number of snapshots recorded [100]\n"
+"    --massif-out-file=<s>     output file name [massif.out.%%p]\n"
    );
    VG_(replacement_malloc_print_usage)();
 }
@@ -1809,9 +1815,6 @@ IRSB* ms_instrument ( VgCallbackClosure* closure,
 //--- Writing snapshots                                    ---//
 //------------------------------------------------------------//
 
-// XXX: do the filename properly, eventually
-static Char* massif_out_file = "massif.out";
-
 #define FP_BUF_SIZE     1024
 Char FP_buf[FP_BUF_SIZE];
 
@@ -2049,6 +2052,69 @@ static void ms_fini(Int exit_status)
 //--- Initialisation                                       ---//
 //------------------------------------------------------------//
 
+// Copies the string, prepending it with the startup working directory, and
+// expanding %p and %q entries.  Returns a new, malloc'd string.
+static Char* expand_file_name(Char* format)
+{
+   static Char base_dir[VKI_PATH_MAX];
+   Int len, i = 0, j = 0;
+   Char* out;
+
+   Bool ok = VG_(get_startup_wd)(base_dir, VKI_PATH_MAX);
+   tl_assert(ok);
+
+   // The 10 is slop, it should be enough in most cases.
+   j = VG_(strlen)(base_dir);
+   len = j + VG_(strlen)(format) + 10;
+   out = VG_(malloc)( len );
+   VG_(strcpy)(out, base_dir);
+
+#define GROW_IF_j_IS_GEQ_THAN(x) \
+   if (j >= x) { \
+      len *= 2; \
+      out = VG_(realloc)(out, len); \
+      OINK(len);\
+   }
+
+   out[j++] = '/';
+   while (format[i]) {
+      if (format[i] != '%') {
+         GROW_IF_j_IS_GEQ_THAN(len);
+         out[j++] = format[i++];
+         
+      } else {
+         // We saw a '%'.  What's next...
+         i++;
+         if      (0   == format[i]) {
+            // At end of string, stop.
+            break;
+         }
+         else if ('%' == format[i]) {
+            // Replace '%%' with '%'.
+            GROW_IF_j_IS_GEQ_THAN(len);
+            out[j++] = format[i++];
+         }
+         else if ('p' == format[i]) {
+            // Print the PID.
+            GROW_IF_j_IS_GEQ_THAN(len - 10);
+            j += VG_(sprintf)(&out[j], "%d", VG_(getpid)());
+            i++;
+         } 
+         else {
+            // Other char, treat both the '%' and its subsequent normally.
+            GROW_IF_j_IS_GEQ_THAN(len - 1);
+            out[j++] = '%';
+            out[j++] = format[i++];
+         }
+      }
+   }
+   GROW_IF_j_IS_GEQ_THAN(len);
+   out[j++] = 0;
+
+   return out;
+}
+
+
 static void ms_post_clo_init(void)
 {
    Int i;
@@ -2106,6 +2172,9 @@ static void ms_post_clo_init(void)
       clear_snapshot( & snapshots[i], /*do_sanity_check*/False );
    }
    sanity_check_snapshots_array();
+
+   // Setup output filename.
+   massif_out_file = expand_file_name(clo_massif_out_file);
 }
 
 static void ms_pre_clo_init(void)
@@ -2152,8 +2221,6 @@ static void ms_pre_clo_init(void)
 
    // Initialise args_for_massif.
    args_for_massif = VG_(newXA)(VG_(malloc), VG_(free), sizeof(HChar*));
-
-   tl_assert( VG_(get_startup_wd)(base_dir, VKI_PATH_MAX) );
 }
 
 VG_DETERMINE_INTERFACE_VERSION(ms_pre_clo_init)
diff --git a/massif/tests/alloc-fns-A.post.exp b/massif/tests/alloc-fns-A.post.exp
index 659ca2e32..9a21059ad 100644
--- a/massif/tests/alloc-fns-A.post.exp
+++ b/massif/tests/alloc-fns-A.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./alloc-fns
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/alloc-fns-A.vgtest b/massif/tests/alloc-fns-A.vgtest
index 9200a80da..ab6615aa4 100644
--- a/massif/tests/alloc-fns-A.vgtest
+++ b/massif/tests/alloc-fns-A.vgtest
@@ -1,4 +1,4 @@
 prog: alloc-fns
-vgopts: --stacks=no --time-unit=B --heap-admin=0
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/alloc-fns-B.post.exp b/massif/tests/alloc-fns-B.post.exp
index 82765e05e..3712260d5 100644
--- a/massif/tests/alloc-fns-B.post.exp
+++ b/massif/tests/alloc-fns-B.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./alloc-fns
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --alloc-fn=a4 --alloc-fn=b4 --alloc-fn=b3 --alloc-fn=c4 --alloc-fn=c3 --alloc-fn=c2 --alloc-fn=d4 --alloc-fn=d3 --alloc-fn=d2 --alloc-fn=d1
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --alloc-fn=a4 --alloc-fn=b4 --alloc-fn=b3 --alloc-fn=c4 --alloc-fn=c3 --alloc-fn=c2 --alloc-fn=d4 --alloc-fn=d3 --alloc-fn=d2 --alloc-fn=d1 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/alloc-fns-B.vgtest b/massif/tests/alloc-fns-B.vgtest
index fab2b46cb..44a6b60a2 100644
--- a/massif/tests/alloc-fns-B.vgtest
+++ b/massif/tests/alloc-fns-B.vgtest
@@ -1,4 +1,4 @@
 prog: alloc-fns
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --alloc-fn=a4 --alloc-fn=b4 --alloc-fn=b3 --alloc-fn=c4 --alloc-fn=c3 --alloc-fn=c2 --alloc-fn=d4 --alloc-fn=d3 --alloc-fn=d2 --alloc-fn=d1
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --alloc-fn=a4 --alloc-fn=b4 --alloc-fn=b3 --alloc-fn=c4 --alloc-fn=c3 --alloc-fn=c2 --alloc-fn=d4 --alloc-fn=d3 --alloc-fn=d2 --alloc-fn=d1 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/basic.post.exp b/massif/tests/basic.post.exp
index 53b967801..8cda5873f 100644
--- a/massif/tests/basic.post.exp
+++ b/massif/tests/basic.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./basic
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/basic.vgtest b/massif/tests/basic.vgtest
index 41124cd27..a4f52a7b5 100644
--- a/massif/tests/basic.vgtest
+++ b/massif/tests/basic.vgtest
@@ -1,4 +1,4 @@
 prog: basic
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/big-alloc.post.exp b/massif/tests/big-alloc.post.exp
index 383645d3d..75c4d34fc 100644
--- a/massif/tests/big-alloc.post.exp
+++ b/massif/tests/big-alloc.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./big-alloc
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/big-alloc.vgtest b/massif/tests/big-alloc.vgtest
index b765673bd..abdefddde 100644
--- a/massif/tests/big-alloc.vgtest
+++ b/massif/tests/big-alloc.vgtest
@@ -1,4 +1,4 @@
 prog: big-alloc
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/culling1.vgtest b/massif/tests/culling1.vgtest
index 50918cd03..81775bed7 100644
--- a/massif/tests/culling1.vgtest
+++ b/massif/tests/culling1.vgtest
@@ -1,4 +1,4 @@
 prog: culling1
-vgopts: -v -v --stacks=no --time-unit=B
+vgopts: -v -v --stacks=no --time-unit=B --massif-out-file=massif.out
 stderr_filter: filter_verbose
 cleanup: rm massif.out
diff --git a/massif/tests/culling2.vgtest b/massif/tests/culling2.vgtest
index 29f13ff3f..a8c6e46cf 100644
--- a/massif/tests/culling2.vgtest
+++ b/massif/tests/culling2.vgtest
@@ -1,4 +1,4 @@
 prog: culling2
-vgopts: -v -v --stacks=no --time-unit=B
+vgopts: -v -v --stacks=no --time-unit=B --massif-out-file=massif.out
 stderr_filter: filter_verbose
 cleanup: rm massif.out
diff --git a/massif/tests/custom_alloc.post.exp b/massif/tests/custom_alloc.post.exp
index 98738b391..8fcc672bb 100644
--- a/massif/tests/custom_alloc.post.exp
+++ b/massif/tests/custom_alloc.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./custom_alloc
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/custom_alloc.vgtest b/massif/tests/custom_alloc.vgtest
index b83b4c0b4..72837df2a 100644
--- a/massif/tests/custom_alloc.vgtest
+++ b/massif/tests/custom_alloc.vgtest
@@ -1,4 +1,4 @@
 prog: custom_alloc
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/deep-A.post.exp b/massif/tests/deep-A.post.exp
index 577974bc3..c84218a5e 100644
--- a/massif/tests/deep-A.post.exp
+++ b/massif/tests/deep-A.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./deep
-Massif arguments:   --stacks=no --time-unit=B --depth=8
+Massif arguments:   --stacks=no --time-unit=B --depth=8 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/deep-A.vgtest b/massif/tests/deep-A.vgtest
index 2126c9590..20a81a772 100644
--- a/massif/tests/deep-A.vgtest
+++ b/massif/tests/deep-A.vgtest
@@ -1,4 +1,4 @@
 prog: deep
-vgopts: --stacks=no --time-unit=B --depth=8
+vgopts: --stacks=no --time-unit=B --depth=8 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/deep-B.post.exp b/massif/tests/deep-B.post.exp
index 4fbfde079..2e4ceed24 100644
--- a/massif/tests/deep-B.post.exp
+++ b/massif/tests/deep-B.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./deep
-Massif arguments:   --stacks=no --time-unit=B --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --depth=8
+Massif arguments:   --stacks=no --time-unit=B --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --depth=8 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/deep-B.vgtest b/massif/tests/deep-B.vgtest
index 6f89e2deb..46c305e7f 100644
--- a/massif/tests/deep-B.vgtest
+++ b/massif/tests/deep-B.vgtest
@@ -1,5 +1,5 @@
 prog: deep
-vgopts: --stacks=no --time-unit=B --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 -v -v --depth=8
+vgopts: --stacks=no --time-unit=B --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 -v -v --depth=8 --massif-out-file=massif.out
 stderr_filter: filter_verbose
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/deep-C.post.exp b/massif/tests/deep-C.post.exp
index 9c6fabba8..06f2a6825 100644
--- a/massif/tests/deep-C.post.exp
+++ b/massif/tests/deep-C.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./deep
-Massif arguments:   --stacks=no --time-unit=B --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --depth=8
+Massif arguments:   --stacks=no --time-unit=B --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --depth=8 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/deep-C.vgtest b/massif/tests/deep-C.vgtest
index cea898ba1..9cda9ed44 100644
--- a/massif/tests/deep-C.vgtest
+++ b/massif/tests/deep-C.vgtest
@@ -1,5 +1,5 @@
 prog: deep
-vgopts: --stacks=no --time-unit=B --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 -v -v --depth=8
+vgopts: --stacks=no --time-unit=B --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 -v -v --depth=8 --massif-out-file=massif.out
 stderr_filter: filter_verbose
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/deep-D.post.exp b/massif/tests/deep-D.post.exp
index fb7fbcdb4..b5da9226f 100644
--- a/massif/tests/deep-D.post.exp
+++ b/massif/tests/deep-D.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./deep
-Massif arguments:   --stacks=no --time-unit=B --alloc-fn=a1 --alloc-fn=a2 --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --alloc-fn=main --depth=20
+Massif arguments:   --stacks=no --time-unit=B --alloc-fn=a1 --alloc-fn=a2 --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --alloc-fn=main --depth=20 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/deep-D.vgtest b/massif/tests/deep-D.vgtest
index 681f8d203..27b92adb3 100644
--- a/massif/tests/deep-D.vgtest
+++ b/massif/tests/deep-D.vgtest
@@ -1,4 +1,4 @@
 prog: deep
-vgopts: --stacks=no --time-unit=B --alloc-fn=a1 --alloc-fn=a2 --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --alloc-fn=main --depth=20
+vgopts: --stacks=no --time-unit=B --alloc-fn=a1 --alloc-fn=a2 --alloc-fn=a3 --alloc-fn=a4 --alloc-fn=a5 --alloc-fn=a6 --alloc-fn=a7 --alloc-fn=a8 --alloc-fn=a9 --alloc-fn=a10 --alloc-fn=a11 --alloc-fn=a12 --alloc-fn=main --depth=20 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses | ../../tests/filter_libc
 cleanup: rm massif.out
diff --git a/massif/tests/ignoring.post.exp b/massif/tests/ignoring.post.exp
index 2fe6475be..e21b19e34 100644
--- a/massif/tests/ignoring.post.exp
+++ b/massif/tests/ignoring.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./ignoring
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/ignoring.vgtest b/massif/tests/ignoring.vgtest
index 62084fe00..0a22e40c7 100644
--- a/massif/tests/ignoring.vgtest
+++ b/massif/tests/ignoring.vgtest
@@ -1,4 +1,4 @@
 prog: ignoring
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/insig.post.exp b/massif/tests/insig.post.exp
index 2e00dc659..b1e5160ac 100644
--- a/massif/tests/insig.post.exp
+++ b/massif/tests/insig.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./insig
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=64
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=64 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/insig.vgtest b/massif/tests/insig.vgtest
index a57d26583..7758d3994 100644
--- a/massif/tests/insig.vgtest
+++ b/massif/tests/insig.vgtest
@@ -1,4 +1,4 @@
 prog: insig
-vgopts: --stacks=no --time-unit=B --heap-admin=64
+vgopts: --stacks=no --time-unit=B --heap-admin=64 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/long-time.post.exp b/massif/tests/long-time.post.exp
index 981915e8e..80e91638a 100644
--- a/massif/tests/long-time.post.exp
+++ b/massif/tests/long-time.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./long-time
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/long-time.vgtest b/massif/tests/long-time.vgtest
index 121ab4b88..83757eea5 100644
--- a/massif/tests/long-time.vgtest
+++ b/massif/tests/long-time.vgtest
@@ -1,4 +1,4 @@
 prog: long-time
-vgopts: --stacks=no --time-unit=B --heap-admin=0
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/new-cpp.post.exp b/massif/tests/new-cpp.post.exp
index cf950db58..31ecbb34e 100644
--- a/massif/tests/new-cpp.post.exp
+++ b/massif/tests/new-cpp.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./new-cpp
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/new-cpp.vgtest b/massif/tests/new-cpp.vgtest
index a31d76412..72471d4d2 100644
--- a/massif/tests/new-cpp.vgtest
+++ b/massif/tests/new-cpp.vgtest
@@ -1,4 +1,4 @@
 prog: new-cpp
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/no-stack-no-heap.post.exp b/massif/tests/no-stack-no-heap.post.exp
index 80291568b..553e37ec1 100644
--- a/massif/tests/no-stack-no-heap.post.exp
+++ b/massif/tests/no-stack-no-heap.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./basic
-Massif arguments:   --stacks=no --heap=no --time-unit=B
+Massif arguments:   --stacks=no --heap=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/no-stack-no-heap.vgtest b/massif/tests/no-stack-no-heap.vgtest
index c07f03c69..17308b1e6 100644
--- a/massif/tests/no-stack-no-heap.vgtest
+++ b/massif/tests/no-stack-no-heap.vgtest
@@ -1,4 +1,4 @@
 prog: basic
-vgopts: --stacks=no --heap=no --time-unit=B
+vgopts: --stacks=no --heap=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/null.post.exp b/massif/tests/null.post.exp
index e8111de85..332b2bf50 100644
--- a/massif/tests/null.post.exp
+++ b/massif/tests/null.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./null
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/null.vgtest b/massif/tests/null.vgtest
index 4e8b80db8..72ac65cc2 100644
--- a/massif/tests/null.vgtest
+++ b/massif/tests/null.vgtest
@@ -1,4 +1,4 @@
 prog: null
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/one.post.exp b/massif/tests/one.post.exp
index d1657d645..a57a4f4c8 100644
--- a/massif/tests/one.post.exp
+++ b/massif/tests/one.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./one
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/one.vgtest b/massif/tests/one.vgtest
index 2d3171de8..38e0f7f5f 100644
--- a/massif/tests/one.vgtest
+++ b/massif/tests/one.vgtest
@@ -1,4 +1,4 @@
 prog: one
-vgopts: --stacks=no --time-unit=B --heap-admin=0
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/overloaded-new.post.exp b/massif/tests/overloaded-new.post.exp
index b8fd6e7d7..bdabf1d8c 100644
--- a/massif/tests/overloaded-new.post.exp
+++ b/massif/tests/overloaded-new.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./overloaded-new
-Massif arguments:   --stacks=no --time-unit=B
+Massif arguments:   --stacks=no --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/overloaded-new.vgtest b/massif/tests/overloaded-new.vgtest
index e12eaae6c..50d2ad030 100644
--- a/massif/tests/overloaded-new.vgtest
+++ b/massif/tests/overloaded-new.vgtest
@@ -1,4 +1,4 @@
 prog: overloaded-new
-vgopts: --stacks=no --time-unit=B
+vgopts: --stacks=no --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/peak.post.exp b/massif/tests/peak.post.exp
index 472f6e78e..d3bd30c9a 100644
--- a/massif/tests/peak.post.exp
+++ b/massif/tests/peak.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./peak
-Massif arguments:   --stacks=no --time-unit=B --peak-inaccuracy=0 --heap-admin=64
+Massif arguments:   --stacks=no --time-unit=B --peak-inaccuracy=0 --heap-admin=64 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/peak.vgtest b/massif/tests/peak.vgtest
index e83274752..d0945ff84 100644
--- a/massif/tests/peak.vgtest
+++ b/massif/tests/peak.vgtest
@@ -1,4 +1,4 @@
 prog: peak
-vgopts: --stacks=no --time-unit=B --peak-inaccuracy=0 --heap-admin=64
+vgopts: --stacks=no --time-unit=B --peak-inaccuracy=0 --heap-admin=64 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/peak2.post.exp b/massif/tests/peak2.post.exp
index 736850cfc..f40f6f78b 100644
--- a/massif/tests/peak2.post.exp
+++ b/massif/tests/peak2.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./peak
-Massif arguments:   --stacks=no --time-unit=B --peak-inaccuracy=10.0 --heap-admin=64
+Massif arguments:   --stacks=no --time-unit=B --peak-inaccuracy=10.0 --heap-admin=64 --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/peak2.vgtest b/massif/tests/peak2.vgtest
index a5b24c52c..4753d0215 100644
--- a/massif/tests/peak2.vgtest
+++ b/massif/tests/peak2.vgtest
@@ -1,5 +1,5 @@
 prog: peak
-vgopts: --stacks=no --time-unit=B -v -v --peak-inaccuracy=10.0 --heap-admin=64
+vgopts: --stacks=no --time-unit=B -v -v --peak-inaccuracy=10.0 --heap-admin=64 --massif-out-file=massif.out
 stderr_filter: filter_verbose
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/realloc.post.exp b/massif/tests/realloc.post.exp
index 36ce5511d..3c14c5b61 100644
--- a/massif/tests/realloc.post.exp
+++ b/massif/tests/realloc.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./realloc
-Massif arguments:   --stacks=no --heap-admin=0 --time-unit=B --threshold=0
+Massif arguments:   --stacks=no --heap-admin=0 --time-unit=B --threshold=0 --massif-out-file=massif.out
 ms_print arguments: --threshold=0 massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/realloc.vgtest b/massif/tests/realloc.vgtest
index 8b7ba7001..c50bad1a5 100644
--- a/massif/tests/realloc.vgtest
+++ b/massif/tests/realloc.vgtest
@@ -1,5 +1,5 @@
 prog: realloc
-vgopts: -v -v --stacks=no --heap-admin=0 --time-unit=B --threshold=0
+vgopts: -v -v --stacks=no --heap-admin=0 --time-unit=B --threshold=0 --massif-out-file=massif.out
 stderr_filter: filter_verbose
 post: perl ../../massif/ms_print --threshold=0 massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/thresholds_0_0.post.exp b/massif/tests/thresholds_0_0.post.exp
index 2fd3d63a7..07c444e08 100644
--- a/massif/tests/thresholds_0_0.post.exp
+++ b/massif/tests/thresholds_0_0.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./thresholds
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=0
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=0 --massif-out-file=massif.out
 ms_print arguments: massif.out --threshold=0
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/thresholds_0_0.vgtest b/massif/tests/thresholds_0_0.vgtest
index c6b3dd7da..5b9f7c685 100644
--- a/massif/tests/thresholds_0_0.vgtest
+++ b/massif/tests/thresholds_0_0.vgtest
@@ -1,4 +1,4 @@
 prog: thresholds
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=0
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=0 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out --threshold=0 | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/thresholds_0_10.post.exp b/massif/tests/thresholds_0_10.post.exp
index c1f3a487a..550aa20db 100644
--- a/massif/tests/thresholds_0_10.post.exp
+++ b/massif/tests/thresholds_0_10.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./thresholds
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=0
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=0 --massif-out-file=massif.out
 ms_print arguments: massif.out --threshold=10
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/thresholds_0_10.vgtest b/massif/tests/thresholds_0_10.vgtest
index 85b823495..58f2a9482 100644
--- a/massif/tests/thresholds_0_10.vgtest
+++ b/massif/tests/thresholds_0_10.vgtest
@@ -1,4 +1,4 @@
 prog: thresholds
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=0
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=0 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out --threshold=10 | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/thresholds_10_0.post.exp b/massif/tests/thresholds_10_0.post.exp
index bef6f8afc..4ff75317e 100644
--- a/massif/tests/thresholds_10_0.post.exp
+++ b/massif/tests/thresholds_10_0.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./thresholds
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=10
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=10 --massif-out-file=massif.out
 ms_print arguments: massif.out --threshold=0
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/thresholds_10_0.vgtest b/massif/tests/thresholds_10_0.vgtest
index c2b8b4389..8c9dd13dd 100644
--- a/massif/tests/thresholds_10_0.vgtest
+++ b/massif/tests/thresholds_10_0.vgtest
@@ -1,4 +1,4 @@
 prog: thresholds
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=10
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=10 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out --threshold=0 | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/thresholds_10_10.post.exp b/massif/tests/thresholds_10_10.post.exp
index 75186076a..ad56e908a 100644
--- a/massif/tests/thresholds_10_10.post.exp
+++ b/massif/tests/thresholds_10_10.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./thresholds
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=10
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=10 --massif-out-file=massif.out
 ms_print arguments: massif.out --threshold=10
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/thresholds_10_10.vgtest b/massif/tests/thresholds_10_10.vgtest
index e829b08df..0b9083b00 100644
--- a/massif/tests/thresholds_10_10.vgtest
+++ b/massif/tests/thresholds_10_10.vgtest
@@ -1,4 +1,4 @@
 prog: thresholds
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=10
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=10 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out --threshold=10 | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/thresholds_5_0.post.exp b/massif/tests/thresholds_5_0.post.exp
index 6ce9bdec1..cb5ee8fa6 100644
--- a/massif/tests/thresholds_5_0.post.exp
+++ b/massif/tests/thresholds_5_0.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./thresholds
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=5
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=5 --massif-out-file=massif.out
 ms_print arguments: massif.out --threshold=0
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/thresholds_5_0.vgtest b/massif/tests/thresholds_5_0.vgtest
index b313c358f..cb5f4457b 100644
--- a/massif/tests/thresholds_5_0.vgtest
+++ b/massif/tests/thresholds_5_0.vgtest
@@ -1,4 +1,4 @@
 prog: thresholds
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=5
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=5 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out --threshold=0 | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/thresholds_5_10.post.exp b/massif/tests/thresholds_5_10.post.exp
index 5101a4276..272e20584 100644
--- a/massif/tests/thresholds_5_10.post.exp
+++ b/massif/tests/thresholds_5_10.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./thresholds
-Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=5
+Massif arguments:   --stacks=no --time-unit=B --heap-admin=0 --threshold=5 --massif-out-file=massif.out
 ms_print arguments: massif.out --threshold=10
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/thresholds_5_10.vgtest b/massif/tests/thresholds_5_10.vgtest
index 615af847e..86a078103 100644
--- a/massif/tests/thresholds_5_10.vgtest
+++ b/massif/tests/thresholds_5_10.vgtest
@@ -1,4 +1,4 @@
 prog: thresholds
-vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=5
+vgopts: --stacks=no --time-unit=B --heap-admin=0 --threshold=5 --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out --threshold=10 | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/zero1.post.exp b/massif/tests/zero1.post.exp
index d27a8628e..979898272 100644
--- a/massif/tests/zero1.post.exp
+++ b/massif/tests/zero1.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./zero
-Massif arguments:   --stacks=no --heap-admin=0 --time-unit=B
+Massif arguments:   --stacks=no --heap-admin=0 --time-unit=B --massif-out-file=massif.out
 ms_print arguments: --threshold=0 massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/zero1.vgtest b/massif/tests/zero1.vgtest
index e32c628c1..95641db14 100644
--- a/massif/tests/zero1.vgtest
+++ b/massif/tests/zero1.vgtest
@@ -1,4 +1,4 @@
 prog: zero
-vgopts: --stacks=no --heap-admin=0 --time-unit=B
+vgopts: --stacks=no --heap-admin=0 --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print --threshold=0 massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out
diff --git a/massif/tests/zero2.post.exp b/massif/tests/zero2.post.exp
index 244c60a92..ba2fea847 100644
--- a/massif/tests/zero2.post.exp
+++ b/massif/tests/zero2.post.exp
@@ -1,6 +1,6 @@
 --------------------------------------------------------------------------------
 Command:            ./zero
-Massif arguments:   --stacks=no --heap-admin=0 --time-unit=B
+Massif arguments:   --stacks=no --heap-admin=0 --time-unit=B --massif-out-file=massif.out
 ms_print arguments: massif.out
 --------------------------------------------------------------------------------
 
diff --git a/massif/tests/zero2.vgtest b/massif/tests/zero2.vgtest
index 8cacf3746..0549a5aa6 100644
--- a/massif/tests/zero2.vgtest
+++ b/massif/tests/zero2.vgtest
@@ -1,4 +1,4 @@
 prog: zero
-vgopts: --stacks=no --heap-admin=0 --time-unit=B
+vgopts: --stacks=no --heap-admin=0 --time-unit=B --massif-out-file=massif.out
 post: perl ../../massif/ms_print massif.out | ../../tests/filter_addresses
 cleanup: rm massif.out