diff --git a/flow/Makefile b/flow/Makefile
index 759e13578d..11e28f8878 100644
--- a/flow/Makefile
+++ b/flow/Makefile
@@ -292,6 +292,34 @@ $(RESULTS_DIR)/1_1_yosys_canonicalize.rtlil: $(RESULTS_DIR)/memories.json
 $(OBJECTS_DIR)/klayout.lyt: $(RESULTS_DIR)/memories.json
 endif
 
+# OpenROAD stages read binary liberty (.blib) files from a cache shared by
+# all designs in $(WORK_HOME)/objects/binary_libs, see
+# scripts/write_binary_libs.tcl. Yosys reads the text libraries.
+.PHONY: binary-libs
+binary-libs:
+	$(UNSET_AND_MAKE) do-binary-libs
+
+.PHONY: do-binary-libs
+do-binary-libs:
+	@mkdir -p $(LOG_DIR)
+	$(RUN_CMD) --log $(abspath $(LOG_DIR)/write_binary_libs.tmp.log) --tee -- $(OPENROAD_CMD) $(SCRIPTS_DIR)/write_binary_libs.tcl
+	mv $(LOG_DIR)/write_binary_libs.tmp.log $(LOG_DIR)/write_binary_libs.log
+
+# do-binary-libs renames its log into place only when it succeeds, so a
+# failed conversion runs again. clean_all and clean_binary_libs delete the
+# log with the cache it records, so the next make fills the cache again.
+$(LOG_DIR)/write_binary_libs.log: $(LIB_FILES) \
+  $(foreach corner,$(shell echo $(CORNERS) | tr '[:lower:]' '[:upper:]'),$($(corner)_LIB_FILES))
+	$(UNSET_AND_MAKE) do-binary-libs
+
+# Order-only, so converting never reruns the flow.
+$(RESULTS_DIR)/1_synth.odb: | $(LOG_DIR)/write_binary_libs.log
+
+.PHONY: clean_binary_libs
+clean_binary_libs:
+	rm -rf $(WORK_HOME)/objects/binary_libs
+	rm -f $(LOG_DIR)/write_binary_libs.log
+
 .PHONY: do-yosys
 do-yosys: yosys-dependencies
 	$(SCRIPTS_DIR)/synth.sh $(SYNTH_SCRIPT) $(LOG_DIR)/1_2_yosys.log
@@ -852,6 +880,7 @@ clean:
 .PHONY: clean_all
 clean_all: clean_synth clean_floorplan clean_place clean_cts clean_route clean_finish clean_metadata clean_abstract
 	rm -rf $(OBJECTS_DIR)
+	rm -f $(LOG_DIR)/write_binary_libs*.log
 
 .PHONY: nuke
 nuke: clean_test clean_issues
diff --git a/flow/scripts/read_liberty.tcl b/flow/scripts/read_liberty.tcl
index 1c013611dd..60816842ff 100644
--- a/flow/scripts/read_liberty.tcl
+++ b/flow/scripts/read_liberty.tcl
@@ -5,7 +5,7 @@ if { [env_var_exists_and_non_empty CORNERS] } {
   foreach corner $::env(CORNERS) {
     set LIBKEY "[string toupper $corner]_LIB_FILES"
     foreach libFile $::env($LIBKEY) {
-      log_cmd read_liberty -corner $corner $libFile
+      log_cmd read_liberty -corner $corner [lib_file_to_read $libFile]
     }
     unset LIBKEY
   }
@@ -13,7 +13,7 @@ if { [env_var_exists_and_non_empty CORNERS] } {
 } else {
   ## no corner
   foreach libFile $::env(LIB_FILES) {
-    log_cmd read_liberty $libFile
+    log_cmd read_liberty [lib_file_to_read $libFile]
   }
 }
 
diff --git a/flow/scripts/util.tcl b/flow/scripts/util.tcl
index 293572e39e..4f984cbee4 100644
--- a/flow/scripts/util.tcl
+++ b/flow/scripts/util.tcl
@@ -506,3 +506,46 @@ proc synth_verilog_files { } {
   }
   return $copies
 }
+
+# Entry of lib_file in the binary liberty (.blib) cache shared by all designs:
+# objects/binary_libs/<platform>/<library>@<size>-<mtime>-<dirhash>.blib, so a
+# changed library gets a new entry and same-named libraries from different
+# directories don't collide. Libraries in the design's directory and those the
+# flow generates are cached per run.
+proc binary_lib_path { lib_file } {
+  set source [file normalize $lib_file]
+  set objects [file join $::env(WORK_HOME) objects]
+  set root [file join $objects binary_libs $::env(PLATFORM)]
+  set run_dirs [list $::env(DESIGN_DIR) $objects [file join $::env(WORK_HOME) results]]
+  foreach dir $run_dirs {
+    if { [string first "[file normalize $dir]/" $source] == 0 } {
+      set root [file join $::env(OBJECTS_DIR) binary_libs]
+      break
+    }
+  }
+  set name [file tail $source]
+  regsub {\.gz$} $name "" name
+  set name [file rootname $name]
+  set dir_hash [format %08x [zlib crc32 [file dirname $source] 0]]
+  return [file join $root "$name@[file size $source]-[file mtime $source]-$dir_hash.blib"]
+}
+
+# Whether this OpenROAD reads blib. An entry missing or written by another
+# version is expected, so its error is not reported.
+proc binary_lib_usable { blib } {
+  suppress_message STA 1900
+  suppress_message STA 1902
+  set usable [expr { ![catch { liberty_binary_info $blib }] }]
+  unsuppress_message STA 1900
+  unsuppress_message STA 1902
+  return $usable
+}
+
+# The cached .blib for lib_file, or lib_file when there is no usable .blib
+proc lib_file_to_read { lib_file } {
+  set blib [binary_lib_path $lib_file]
+  if { [binary_lib_usable $blib] } {
+    return $blib
+  }
+  return $lib_file
+}
diff --git a/flow/scripts/write_binary_libs.tcl b/flow/scripts/write_binary_libs.tcl
new file mode 100644
index 0000000000..a663fdc10a
--- /dev/null
+++ b/flow/scripts/write_binary_libs.tcl
@@ -0,0 +1,40 @@
+# Fill the binary liberty (.blib) cache with the libraries the OpenROAD stages read
+source $::env(SCRIPTS_DIR)/util.tcl
+
+set lib_files {}
+if { [env_var_exists_and_non_empty CORNERS] } {
+  foreach corner $::env(CORNERS) {
+    lappend lib_files {*}$::env([string toupper $corner]_LIB_FILES)
+  }
+} else {
+  lappend lib_files {*}$::env(LIB_FILES)
+}
+
+set written 0
+set cached 0
+array set seen {}
+foreach lib_file $lib_files {
+  set blib [binary_lib_path $lib_file]
+  if { [info exists seen($blib)] } {
+    continue
+  }
+  set seen($blib) 1
+  if { [binary_lib_usable $blib] } {
+    incr cached
+    continue
+  }
+  # Publish with a rename, so concurrent flows never read a partial file
+  set tmp "$blib.tmp.[info hostname].[pid]"
+  if {
+    [catch {
+      file mkdir [file dirname $blib]
+      log_cmd write_liberty_binary $lib_file $tmp
+      file rename -force $tmp $blib
+    } msg]
+  } {
+    file delete -force $tmp
+    error "Could not write $blib: $msg"
+  }
+  incr written
+}
+puts "Binary liberty files: $written written, $cached already cached"
diff --git a/flow/util/genReport.py b/flow/util/genReport.py
index 52ec6115dd..cf70e628bc 100755
--- a/flow/util/genReport.py
+++ b/flow/util/genReport.py
@@ -299,13 +299,15 @@ def write_summary():
     # check if design ran to completion without errors or warnings
     d["log_errors"] = list()
     d["log_warnings"] = list()
-    d["last_log"] = ""
+    d["last_log"] = max(
+        (name for name in files if name.endswith(".log")),
+        key=lambda name: os.path.getmtime(os.path.join(log_dir, name)),
+        default="",
+    )
     for name_ in sorted(files):
         temp_e, temp_w = parse_messages(os.path.join(log_dir, name_))
         d["log_errors"] += temp_e
         d["log_warnings"] += temp_w
-        if name_.endswith(".log"):
-            d["last_log"] = name_
     d["finished"] = any(name in files for name in LAST_EXPECTED_LOG)
 
     # check if metrics generation had issues