diff --git a/VERSION b/VERSION
index 1f5b7e5b..2c1ea239 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-8.3.314
+8.3.315
diff --git a/doc/html/def.html b/doc/html/def.html
index 083ab6ab..f9d4f000 100644
--- a/doc/html/def.html
+++ b/doc/html/def.html
@@ -30,6 +30,7 @@ Read or write DEF format files.
          where <I>option</I> is one of the following:
 	 <DL>
 	   <DT> <B>read</B> <I>filename</I> [<B>-labels</B>] [<B>-annotate</B>]
+			[<B>-noblockage</B>]
 	   <DD> Read a DEF file <I>filename</I>[<B>.def</B>]
 	   <DT> <B>write</B> [<I>cell</I>] [<B>-units</B> <I>value</I>]
 	   <DD> Write DEF for current or indicated cell named <I>cell</I>
@@ -75,6 +76,14 @@ Read or write DEF format files.
       useful for labeling all of the regular nets if the DEF file was
       previously read without the <B>-labels</B> option. <P>
 
+      The "<B>-noblockage</B>" option will ignore all BLOCKAGES sections
+      in the DEF file, in effect producing only mask layer geometry.  If
+      not specified, then layer BLOCKAGES in the DEF file are treated
+      like obstructions in LEF files, and translated into obstruction
+      layers in magic (per the definition of obstruction layers in either
+      the "lef" section of the magic technology file, or in a technology
+      LEF file read prior to reading the DEF file). <P>
+
    </BLOCKQUOTE>
 
 <H3>Implementation Notes:</H3>
diff --git a/lef/defRead.c b/lef/defRead.c
index 9ec6a150..e326fd6b 100644
--- a/lef/defRead.c
+++ b/lef/defRead.c
@@ -2333,10 +2333,11 @@ enum def_sections {DEF_VERSION = 0, DEF_NAMESCASESENSITIVE,
 	DEF_NONDEFAULTRULES, DEF_END};
 
 void
-DefRead(inName, dolabels, annotate)
+DefRead(inName, dolabels, annotate, noblockage)
     char *inName;
     bool dolabels;
     bool annotate;
+    bool noblockage;
 {
     CellDef *rootDef;
     FILE *f;
@@ -2560,7 +2561,7 @@ DefRead(inName, dolabels, annotate)
 		token = LefNextToken(f, TRUE);
 		if (sscanf(token, "%d", &total) != 1) total = 0;
 		LefEndStatement(f);
-		if (annotate)
+		if (annotate || noblockage)
 		    LefSkipSection(f, sections[DEF_BLOCKAGES]);
 		else
 		    DefReadBlockages(f, rootDef, sections[DEF_BLOCKAGES],
diff --git a/lef/lefCmd.c b/lef/lefCmd.c
index fd78ae1b..32c6302c 100644
--- a/lef/lefCmd.c
+++ b/lef/lefCmd.c
@@ -123,6 +123,10 @@ CmdLef(w, cmd)
 					 * created from any DEF files, which
 					 * will be used for label annotation only.
 					 */
+    bool defNoBlockage = FALSE;		/* Indicates that BLOCKAGE geometry in
+					 * the DEF file should be ignored; only
+					 * mask geometry will be generated.
+					 */
     static char *cmdLefOption[] =
     {
 	"read [filename]		read a LEF file filename[.lef]\n"
@@ -145,7 +149,8 @@ CmdLef(w, cmd)
     {
 	"read [filename]		read a DEF file filename[.def]\n"
 	"    read [filename] -labels	read a DEF file with net labeling\n"
-	"    read [filename] -annotate	read a DEF file for net annotation only",
+	"    read [filename] -annotate	read a DEF file for net annotation only\n",
+	"    read [filename] -noblockage	read a DEF file (mask layers only).",
 	"write [cell] [-allspecial]	write DEF for current or indicated cell",
 	"writeall			(use \"flatten -nosubckt\" + \"def"
 					" write\" instead)",
@@ -216,6 +221,13 @@ CmdLef(w, cmd)
 			    else
 				defLabelNets = TRUE;
 			}
+			else if (!strncmp(cmd->tx_argv[i], "-noblock", 8))
+			{
+			    if (is_lef)
+				TxPrintf("The \"-noblockage\" option is only for def read\n");
+			    else
+				defNoBlockage = TRUE;
+			}
 		    }
 		}
 	    }
@@ -226,7 +238,7 @@ CmdLef(w, cmd)
 	    if (is_lef)
 		LefRead(namep, lefImport, lefAnnotate, lefDateStamp);
 	    else
-		DefRead(namep, defLabelNets, defAnnotate);
+		DefRead(namep, defLabelNets, defAnnotate, defNoBlockage);
 	    break;
 	case LEF_WRITEALL:
 	    if (!is_lef)