Index: core/src/java/org/apache/lucene/index/LogMergePolicy.java
===================================================================
--- core/src/java/org/apache/lucene/index/LogMergePolicy.java	(revision 1376393)
+++ core/src/java/org/apache/lucene/index/LogMergePolicy.java	(working copy)
@@ -64,6 +64,13 @@
    *  @see #setNoCFSRatio */
   public static final double DEFAULT_NO_CFS_RATIO = 0.1;
 
+  /** Default maxCFSSegmentSize value allows compound file
+   * for a segment of any size. The actual file format is
+   * still subject to noCFSRatio.
+   * @see #setMaxCFSSegmentSizeMB(double)
+   */
+  public static final long DEFAULT_MAX_CFS_SEGMENT_SIZE = Long.MAX_VALUE;
+
   protected int mergeFactor = DEFAULT_MERGE_FACTOR;
 
   protected long minMergeSize;
@@ -74,6 +81,7 @@
   protected int maxMergeDocs = DEFAULT_MAX_MERGE_DOCS;
 
   protected double noCFSRatio = DEFAULT_NO_CFS_RATIO;
+  protected long maxCFSSegmentSize = DEFAULT_MAX_CFS_SEGMENT_SIZE;
 
   protected boolean calibrateSizeByDeletes = true;
   
@@ -136,21 +144,21 @@
   // Javadoc inherited
   @Override
   public boolean useCompoundFile(SegmentInfos infos, SegmentInfoPerCommit mergedInfo) throws IOException {
-    final boolean doCFS;
-
-    if (!useCompoundFile) {
-      doCFS = false;
-    } else if (noCFSRatio == 1.0) {
-      doCFS = true;
-    } else {
-      long totalSize = 0;
-      for (SegmentInfoPerCommit info : infos) {
-        totalSize += size(info);
-      }
-
-      doCFS = size(mergedInfo) <= noCFSRatio * totalSize;
+    if (!getUseCompoundFile()) {
+      return false;
     }
-    return doCFS;
+    long mergedInfoSize = size(mergedInfo);
+    if (mergedInfoSize > maxCFSSegmentSize) {
+      return false;
+    }
+    if (getNoCFSRatio() >= 1.0) {
+      return true;
+    }
+    long totalSize = 0;
+    for (SegmentInfoPerCommit info : infos) {
+      totalSize += size(info);
+    }
+    return mergedInfoSize <= getNoCFSRatio() * totalSize;
   }
 
   /** Sets whether compound file format should be used for
@@ -674,9 +682,24 @@
     sb.append("calibrateSizeByDeletes=").append(calibrateSizeByDeletes).append(", ");
     sb.append("maxMergeDocs=").append(maxMergeDocs).append(", ");
     sb.append("useCompoundFile=").append(useCompoundFile).append(", ");
+    sb.append("maxCFSSegmentSizeMB=").append(maxCFSSegmentSize/1024/1024.).append(", ");
     sb.append("noCFSRatio=").append(noCFSRatio);
     sb.append("]");
     return sb.toString();
   }
-  
+
+  /** Returns the largest size allowed for a compound file segment */
+  public final double getMaxCFSSegmentSizeMB() {
+    return maxCFSSegmentSize/1024/1024.;
+  }
+
+  /** If a merged segment will be more than this value,
+   *  leave the segment as
+   *  non-compound file even if compound file is enabled.
+   *  Set this to Long.MAX_VALUE (default) and noCFSRatio to 1.0
+   *  to always use CFS regardless of merge size. */
+  public final void setMaxCFSSegmentSizeMB(double v) {
+    this.maxCFSSegmentSize = (long) (v*1024*1024);
+  }
+
 }
Index: core/src/java/org/apache/lucene/index/TieredMergePolicy.java
===================================================================
--- core/src/java/org/apache/lucene/index/TieredMergePolicy.java	(revision 1376393)
+++ core/src/java/org/apache/lucene/index/TieredMergePolicy.java	(working copy)
@@ -84,6 +84,7 @@
   private double forceMergeDeletesPctAllowed = 10.0;
   private boolean useCompoundFile = true;
   private double noCFSRatio = 0.1;
+  private long maxCFSSegmentSize = Long.MAX_VALUE;
   private double reclaimDeletesWeight = 2.0;
 
   /** Maximum number of segments to be merged at a time
@@ -602,21 +603,21 @@
 
   @Override
   public boolean useCompoundFile(SegmentInfos infos, SegmentInfoPerCommit mergedInfo) throws IOException {
-    final boolean doCFS;
-
-    if (!useCompoundFile) {
-      doCFS = false;
-    } else if (noCFSRatio == 1.0) {
-      doCFS = true;
-    } else {
-      long totalSize = 0;
-      for (SegmentInfoPerCommit info : infos) {
+    if (!getUseCompoundFile()) {
+        return false;
+    }
+    long mergedInfoSize = size(mergedInfo);
+    if (mergedInfoSize > maxCFSSegmentSize) {
+        return false;
+    }
+    if (getNoCFSRatio() >= 1.0) {
+        return true;
+    }
+    long totalSize = 0;
+    for (SegmentInfoPerCommit info : infos) {
         totalSize += size(info);
-      }
-
-      doCFS = size(mergedInfo) <= noCFSRatio * totalSize;
     }
-    return doCFS;
+    return mergedInfoSize <= getNoCFSRatio() * totalSize;
   }
 
   @Override
@@ -629,7 +630,7 @@
     boolean hasDeletions = w.numDeletedDocs(info) > 0;
     return !hasDeletions &&
       info.info.dir == w.getDirectory() &&
-      (info.info.getUseCompoundFile() == useCompoundFile || noCFSRatio < 1.0);
+      (info.info.getUseCompoundFile() == useCompoundFile || noCFSRatio < 1.0 || maxCFSSegmentSize < Long.MAX_VALUE);
   }
 
   // Segment size in bytes, pro-rated by % deleted
@@ -664,7 +665,22 @@
     sb.append("forceMergeDeletesPctAllowed=").append(forceMergeDeletesPctAllowed).append(", ");
     sb.append("segmentsPerTier=").append(segsPerTier).append(", ");
     sb.append("useCompoundFile=").append(useCompoundFile).append(", ");
+    sb.append("maxCFSSegmentSizeMB=").append(maxCFSSegmentSize/1024/1024.).append(", ");
     sb.append("noCFSRatio=").append(noCFSRatio);
     return sb.toString();
   }
+
+  /** Returns the largest size allowed for a compound file segment */
+  public final double getMaxCFSSegmentSizeMB() {
+    return maxCFSSegmentSize/1024/1024.;
+  }
+
+  /** If a merged segment will be more than this value,
+   *  leave the segment as
+   *  non-compound file even if compound file is enabled.
+   *  Set this to Long.MAX_VALUE (default) and noCFSRatio to 1.0
+   *  to always use CFS regardless of merge size. */
+  public final void setMaxCFSSegmentSizeMB(double v) {
+    this.maxCFSSegmentSize = (long) (v*1024*1024);
+  }
 }