diff --git a/build/LICENSE b/build/LICENSE
new file mode 100644
index 000000000..e69de29bb
diff --git a/programs/fileio.c b/programs/fileio.c
index 09687c67a..4691003bb 100644
--- a/programs/fileio.c
+++ b/programs/fileio.c
@@ -628,6 +628,102 @@ static size_t FIO_createDictBuffer(void** bufferPtr, const char* fileName)
     return (size_t)fileSize;
 }
 
+
+
+/* FIO_checkFilenameCollisions() :
+ * Checks for and warns if there are any files that would have the same output path
+ */
+int FIO_checkFilenameCollisions(const char** filenameTable, unsigned nbFiles) {
+    const char **filenameTableSorted, *c, *prevElem, *filename;
+    unsigned u;
+
+    #if defined(_MSC_VER) || defined(__MINGW32__) || defined (__MSVCRT__) /* windows support */
+    c = "\\";
+    #else
+    c = "/";
+    #endif
+
+    filenameTableSorted = (const char**) malloc(sizeof(char*) * nbFiles);
+    if (!filenameTableSorted) {
+        DISPLAY("Unable to malloc new str array, not checking for name collisions\n");
+        return 1;
+    }
+    
+    for (u = 0; u < nbFiles; ++u) {
+        filename = strrchr(filenameTable[u], c[0]);
+        if (filename == NULL) {
+            filenameTableSorted[u] = filenameTable[u];
+        } else {
+            filenameTableSorted[u] = filename+1;
+        }
+    }
+
+    qsort((void*)filenameTableSorted, nbFiles, sizeof(char*), UTIL_compareStr);
+    prevElem = filenameTableSorted[0];
+    for (u = 1; u < nbFiles; ++u) {
+        if (strcmp(prevElem, filenameTableSorted[u]) == 0) {
+            DISPLAY("WARNING: Two files have same filename: %s\n", prevElem);
+        }
+        prevElem = filenameTableSorted[u];
+    }
+
+    free((void*)filenameTableSorted);
+    return 0;
+}
+
+/* FIO_createFilename_fromOutDir() :
+ * Takes a source file name and specified output directory, and
+ * allocates memory for and returns a pointer to final path.
+ * This function never returns an error (it may abort() in case of pb)
+ */
+static char*
+FIO_createFilename_fromOutDir(const char* srcFilename, const char* outDirName, const size_t suffixLen)
+{
+    const char* c, *filenameBegin;
+    char* filename, *result;
+    size_t finalPathLen;
+
+    #if defined(_MSC_VER) || defined(__MINGW32__) || defined (__MSVCRT__) /* windows support */
+    c = "\\";
+    #else
+    c = "/";
+    #endif
+
+    finalPathLen = strlen(outDirName);
+    filenameBegin = strrchr(srcFilename, c[0]);
+    if (filenameBegin == NULL) {
+        filename = (char*) malloc((strlen(srcFilename)+1) * sizeof(char));
+        if (!filename) {
+            EXM_THROW(30, "zstd: %s", strerror(errno));
+        }
+        strcpy(filename, srcFilename);
+    } else {
+        filename = (char*) malloc((strlen(filenameBegin+1)+1) * sizeof(char));
+        if (!filename) {
+            EXM_THROW(30, "zstd: %s", strerror(errno));
+        }
+        strcpy(filename, filenameBegin+1);
+    }
+
+    finalPathLen += strlen(filename);
+    result = (char*) malloc((finalPathLen+suffixLen+30) * sizeof(char));
+    if (!result) {
+        free(filename);
+        EXM_THROW(30, "zstd: %s", strerror(errno));
+    }
+
+    strcpy(result, outDirName);
+    if (outDirName[strlen(outDirName)-1] == c[0]) {
+        strcat(result, filename);
+    } else {  
+        strcat(result, c);
+        strcat(result, filename);
+    }
+
+    free(filename);
+    return result;
+}
+
 #ifndef ZSTD_NOCOMPRESS
 
 /* **********************************************************************
@@ -1276,9 +1372,7 @@ static int FIO_compressFilename_dstFile(FIO_prefs_t* const prefs,
     int result;
     stat_t statbuf;
     int transfer_permissions = 0;
-
     assert(ress.srcFile != NULL);
-
     if (ress.dstFile == NULL) {
         closeDstFile = 1;
         DISPLAYLEVEL(6, "FIO_compressFilename_dstFile: opening dst: %s", dstFileName);
@@ -1369,11 +1463,9 @@ FIO_compressFilename_srcFile(FIO_prefs_t* const prefs,
     return result;
 }
 
-
-int FIO_compressFilename(FIO_prefs_t* const prefs,
-                         const char* dstFileName, const char* srcFileName,
-                         const char* dictFileName, int compressionLevel,
-                         ZSTD_compressionParameters comprParams)
+int FIO_compressFilename(FIO_prefs_t* const prefs, const char* dstFileName,
+                         const char* srcFileName, const char* dictFileName,
+                         int compressionLevel,  ZSTD_compressionParameters comprParams)
 {
     cRess_t const ress = FIO_createCResources(prefs, dictFileName, compressionLevel, comprParams);
     int const result = FIO_compressFilename_srcFile(prefs, ress, dstFileName, srcFileName, compressionLevel);
@@ -1383,21 +1475,25 @@ int FIO_compressFilename(FIO_prefs_t* const prefs,
     return result;
 }
 
-
 /* FIO_determineCompressedName() :
  * create a destination filename for compressed srcFileName.
  * @return a pointer to it.
  * This function never returns an error (it may abort() in case of pb)
  */
 static const char*
-FIO_determineCompressedName(const char* srcFileName, const char* suffix)
+FIO_determineCompressedName(const char* srcFileName, const char* outDirName, const char* suffix)
 {
     static size_t dfnbCapacity = 0;
     static char* dstFileNameBuffer = NULL;   /* using static allocation : this function cannot be multi-threaded */
-
-    size_t const sfnSize = strlen(srcFileName);
+    char* outDirFilename = NULL;
+    size_t sfnSize = strlen(srcFileName);
     size_t const suffixSize = strlen(suffix);
-
+    if (outDirName) {
+        outDirFilename = FIO_createFilename_fromOutDir(srcFileName, outDirName, suffixSize);
+        sfnSize = strlen(outDirFilename);
+        assert(outDirFilename != NULL);
+    }
+    
     if (dfnbCapacity <= sfnSize+suffixSize+1) {
         /* resize buffer for dstName */
         free(dstFileNameBuffer);
@@ -1405,23 +1501,30 @@ FIO_determineCompressedName(const char* srcFileName, const char* suffix)
         dstFileNameBuffer = (char*)malloc(dfnbCapacity);
         if (!dstFileNameBuffer) {
             EXM_THROW(30, "zstd: %s", strerror(errno));
-    }   }
+        }
+    }
     assert(dstFileNameBuffer != NULL);
-    memcpy(dstFileNameBuffer, srcFileName, sfnSize);
-    memcpy(dstFileNameBuffer+sfnSize, suffix, suffixSize+1 /* Include terminating null */);
 
+    if (outDirFilename) {
+        memcpy(dstFileNameBuffer, outDirFilename, sfnSize);
+        free(outDirFilename);
+    } else {
+        memcpy(dstFileNameBuffer, srcFileName, sfnSize);
+    }
+    memcpy(dstFileNameBuffer+sfnSize, suffix, suffixSize+1 /* Include terminating null */);
     return dstFileNameBuffer;
 }
 
 
 /* FIO_compressMultipleFilenames() :
  * compress nbFiles files
- * into one destination (outFileName)
- * or into one file each (outFileName == NULL, but suffix != NULL).
+ * into either one destination (outFileName),
+ * or into one file each (outFileName == NULL, but suffix != NULL),
+ * or into a destination folder (specified with -O)
  */
-int FIO_compressMultipleFilenames(FIO_prefs_t* const prefs,
-                                  const char** inFileNamesTable, unsigned nbFiles,
-                                  const char* outFileName, const char* suffix,
+int FIO_compressMultipleFilenames(FIO_prefs_t* const prefs, const char** inFileNamesTable,
+                                  const char* outDirName, unsigned nbFiles, 
+                                  const char* outFileName, const char* suffix, 
                                   const char* dictFileName, int compressionLevel,
                                   ZSTD_compressionParameters comprParams)
 {
@@ -1430,7 +1533,6 @@ int FIO_compressMultipleFilenames(FIO_prefs_t* const prefs,
 
     /* init */
     assert(outFileName != NULL || suffix != NULL);
-
     if (outFileName != NULL) {   /* output into a single destination (stdout typically) */
         ress.dstFile = FIO_openDstFile(prefs, NULL, outFileName);
         if (ress.dstFile == NULL) {  /* could not open outFileName */
@@ -1448,9 +1550,12 @@ int FIO_compressMultipleFilenames(FIO_prefs_t* const prefs,
         unsigned u;
         for (u=0; u<nbFiles; u++) {
             const char* const srcFileName = inFileNamesTable[u];
-            const char* const dstFileName = FIO_determineCompressedName(srcFileName, suffix);  /* cannot fail */
+            const char* const dstFileName = FIO_determineCompressedName(srcFileName, outDirName, suffix);  /* cannot fail */
             error |= FIO_compressFilename_srcFile(prefs, ress, dstFileName, srcFileName, compressionLevel);
-    }   }
+        }
+        if (outDirName)
+            FIO_checkFilenameCollisions(inFileNamesTable ,nbFiles);
+    }
 
     FIO_freeCResources(ress);
     return error;
@@ -2166,13 +2271,14 @@ int FIO_decompressFilename(FIO_prefs_t* const prefs,
  * @return a pointer to it.
  * @return == NULL if there is an error */
 static const char*
-FIO_determineDstName(const char* srcFileName)
+FIO_determineDstName(const char* srcFileName, const char* outDirName)
 {
     static size_t dfnbCapacity = 0;
     static char* dstFileNameBuffer = NULL;   /* using static allocation : this function cannot be multi-threaded */
-
-    size_t const sfnSize = strlen(srcFileName);
+    char* outDirFilename = NULL;
+    size_t sfnSize = strlen(srcFileName);
     size_t suffixSize;
+    
     const char* const suffixPtr = strrchr(srcFileName, '.');
     if (suffixPtr == NULL) {
         DISPLAYLEVEL(1, "zstd: %s: unknown suffix -- ignored \n",
@@ -2210,19 +2316,29 @@ FIO_determineDstName(const char* srcFileName)
                      srcFileName, suffixlist);
         return NULL;
     }
+    if (outDirName) {
+        outDirFilename = FIO_createFilename_fromOutDir(srcFileName, outDirName, 0);
+        sfnSize = strlen(outDirFilename);
+        assert(outDirFilename != NULL);
+    }
 
-    /* allocate enough space to write dstFilename into it */
     if (dfnbCapacity+suffixSize <= sfnSize+1) {
+        /* allocate enough space to write dstFilename into it */
         free(dstFileNameBuffer);
         dfnbCapacity = sfnSize + 20;
         dstFileNameBuffer = (char*)malloc(dfnbCapacity);
         if (dstFileNameBuffer==NULL)
-            EXM_THROW(74, "%s : not enough memory for dstFileName", strerror(errno));
+            EXM_THROW(74, "%s : not enough memory for dstFileName", strerror(errno)); 
     }
 
     /* return dst name == src name truncated from suffix */
     assert(dstFileNameBuffer != NULL);
-    memcpy(dstFileNameBuffer, srcFileName, sfnSize - suffixSize);
+    if (outDirFilename) {
+        memcpy(dstFileNameBuffer, outDirFilename, sfnSize - suffixSize);
+        free(outDirFilename);
+    } else {
+        memcpy(dstFileNameBuffer, srcFileName, sfnSize - suffixSize);
+    }
     dstFileNameBuffer[sfnSize-suffixSize] = '\0';
     return dstFileNameBuffer;
 
@@ -2232,8 +2348,8 @@ FIO_determineDstName(const char* srcFileName)
 
 int
 FIO_decompressMultipleFilenames(FIO_prefs_t* const prefs,
-                                const char* srcNamesTable[], unsigned nbFiles,
-                                const char* outFileName,
+                                const char** srcNamesTable, unsigned nbFiles,
+                                const char* outDirName, const char* outFileName,
                                 const char* dictFileName)
 {
     int error = 0;
@@ -2252,19 +2368,19 @@ FIO_decompressMultipleFilenames(FIO_prefs_t* const prefs,
         unsigned u;
         for (u=0; u<nbFiles; u++) {   /* create dstFileName */
             const char* const srcFileName = srcNamesTable[u];
-            const char* const dstFileName = FIO_determineDstName(srcFileName);
+            const char* const dstFileName = FIO_determineDstName(srcFileName, outDirName);
             if (dstFileName == NULL) { error=1; continue; }
 
             error |= FIO_decompressSrcFile(prefs, ress, dstFileName, srcFileName);
         }
+        if (outDirName)
+            FIO_checkFilenameCollisions(srcNamesTable ,nbFiles);
     }
 
     FIO_freeDResources(ress);
     return error;
 }
 
-
-
 /* **************************************************************************
  *  .zst file info (--list command)
  ***************************************************************************/
diff --git a/programs/fileio.h b/programs/fileio.h
index 096d90b5c..ded1c0373 100644
--- a/programs/fileio.h
+++ b/programs/fileio.h
@@ -87,8 +87,9 @@ void FIO_setNotificationLevel(int level);
 /** FIO_compressFilename() :
     @return : 0 == ok;  1 == pb with src file. */
 int FIO_compressFilename (FIO_prefs_t* const prefs,
-                          const char* outfilename, const char* infilename, const char* dictFileName,
-                          int compressionLevel, ZSTD_compressionParameters comprParams);
+                          const char* outfilename, const char* infilename,
+                          const char* dictFileName, int compressionLevel,
+                          ZSTD_compressionParameters comprParams);
 
 /** FIO_decompressFilename() :
     @return : 0 == ok;  1 == pb with src file. */
@@ -103,19 +104,24 @@ int FIO_listMultipleFiles(unsigned numFiles, const char** filenameTable, int dis
 ***************************************/
 /** FIO_compressMultipleFilenames() :
     @return : nb of missing files */
-int FIO_compressMultipleFilenames(FIO_prefs_t* const prefs,
-                                  const char** srcNamesTable, unsigned nbFiles,
-                                  const char* outFileName, const char* suffix,
-                                  const char* dictFileName, int compressionLevel,
+int FIO_compressMultipleFilenames(FIO_prefs_t* const prefs, const char** inFileNamesTable,
+                                  const char* outDirName, unsigned nbFiles, 
+                                  const char* outFileName, const char* suffix, 
+                                  const char* dictFileName, int compressionLevel, 
                                   ZSTD_compressionParameters comprParams);
 
 /** FIO_decompressMultipleFilenames() :
     @return : nb of missing or skipped files */
 int FIO_decompressMultipleFilenames(FIO_prefs_t* const prefs,
                                     const char** srcNamesTable, unsigned nbFiles,
+                                    const char* outDirName,
                                     const char* outFileName,
                                     const char* dictFileName);
 
+/* FIO_checkFilenameCollisions() :
+ * Checks for and warns if thereå are any files that would have the same output path
+ */
+int FIO_checkFilenameCollisions(const char** filenameTable, unsigned nbFiles);
 
 /*-*************************************
 *  Advanced stuff (should actually be hosted elsewhere)
diff --git a/programs/util.c b/programs/util.c
index 3988295d4..ca141eb27 100644
--- a/programs/util.c
+++ b/programs/util.c
@@ -20,6 +20,9 @@ extern "C" {
 #include <errno.h>
 #include <assert.h>
 
+#if defined(_MSC_VER) || defined(__MINGW32__) || defined (__MSVCRT__)
+#include <direct.h>     /* needed for _mkdir in windows */
+#endif
 
 int UTIL_fileExist(const char* filename)
 {
@@ -98,6 +101,10 @@ U32 UTIL_isDirectory(const char* infilename)
     return 0;
 }
 
+int UTIL_compareStr(const void *p1, const void *p2) {
+    return strcmp(* (char * const *) p1, * (char * const *) p2);
+}
+
 int UTIL_isSameFile(const char* file1, const char* file2)
 {
 #if defined(_MSC_VER)
diff --git a/programs/util.h b/programs/util.h
index 0080b63c7..c73f7e9b0 100644
--- a/programs/util.h
+++ b/programs/util.h
@@ -134,6 +134,7 @@ int UTIL_setFileStat(const char* filename, stat_t* statbuf);
 U32 UTIL_isDirectory(const char* infilename);
 int UTIL_getFileStat(const char* infilename, stat_t* statbuf);
 int UTIL_isSameFile(const char* file1, const char* file2);
+int UTIL_compareStr(const void *p1, const void *p2);
 
 U32 UTIL_isLink(const char* infilename);
 #define UTIL_FILESIZE_UNKNOWN  ((U64)(-1))
diff --git a/programs/zstdcli.c b/programs/zstdcli.c
index 98df728a9..ae53d2c39 100644
--- a/programs/zstdcli.c
+++ b/programs/zstdcli.c
@@ -136,6 +136,7 @@ static int usage_advanced(const char* programName)
     DISPLAY( " -q     : suppress warnings; specify twice to suppress errors too\n");
     DISPLAY( " -c     : force write to standard output, even if it is the console\n");
     DISPLAY( " -l     : print information about zstd compressed files \n");
+    DISPLAY( " --output-dir-flat directory: results stored into `directory`. Filename collisions mean first file will be compressed. With -f, the last file will be compressed.\n");
 #ifndef ZSTD_NOCOMPRESS
     DISPLAY( "--ultra : enable levels beyond %i, up to %i (requires more memory)\n", ZSTDCLI_CLEVEL_MAX, ZSTD_maxCLevel());
     DISPLAY( "--long[=#]: enable long distance matching with given window log (default: %u)\n", g_defaultMaxWindowLog);
@@ -562,6 +563,7 @@ int main(int argCount, const char* argv[])
         adaptMax = MAXCLEVEL,
         rsyncable = 0,
         nextArgumentIsOutFileName = 0,
+        nextArgumentIsOutDirName = 0,
         nextArgumentIsMaxDict = 0,
         nextArgumentIsDictID = 0,
         nextArgumentsAreFiles = 0,
@@ -586,6 +588,7 @@ int main(int argCount, const char* argv[])
     unsigned filenameIdx = 0;
     const char* programName = argv[0];
     const char* outFileName = NULL;
+    const char* outDirName = NULL;
     const char* dictFileName = NULL;
     const char* suffix = ZSTD_EXTENSION;
     unsigned maxDictSize = g_defaultMaxDictSize;
@@ -686,6 +689,7 @@ int main(int argCount, const char* argv[])
                     if (!strcmp(argument, "--keep")) { FIO_setRemoveSrcFile(prefs, 0); continue; }
                     if (!strcmp(argument, "--rm")) { FIO_setRemoveSrcFile(prefs, 1); continue; }
                     if (!strcmp(argument, "--priority=rt")) { setRealTimePrio = 1; continue; }
+                    if (!strcmp(argument, "--output-dir-flat")) {nextArgumentIsOutDirName=1; lastCommand=1; continue; }
                     if (!strcmp(argument, "--adapt")) { adapt = 1; continue; }
                     if (longCommandWArg(&argument, "--adapt=")) { adapt = 1; if (!parseAdaptParameters(argument, &adaptMin, &adaptMax)) CLEAN_RETURN(badusage(programName)); continue; }
                     if (!strcmp(argument, "--single-thread")) { nbWorkers = 0; singleThread = 1; continue; }
@@ -852,7 +856,7 @@ int main(int argCount, const char* argv[])
 
                         /* destination file name */
                     case 'o': nextArgumentIsOutFileName=1; lastCommand=1; argument++; break;
-
+                   
                         /* limit decompression memory */
                     case 'M':
                         argument++;
@@ -965,6 +969,13 @@ int main(int argCount, const char* argv[])
             continue;
         }
 
+        if (nextArgumentIsOutDirName) {
+            nextArgumentIsOutDirName = 0;
+            lastCommand = 0;
+            outDirName = argument;
+            continue;
+        }
+
         /* add filename to list */
         filenameTable[filenameIdx++] = argument;
     }
@@ -1166,7 +1177,7 @@ int main(int argCount, const char* argv[])
         if ((filenameIdx==1) && outFileName)
           operationResult = FIO_compressFilename(prefs, outFileName, filenameTable[0], dictFileName, cLevel, compressionParams);
         else
-          operationResult = FIO_compressMultipleFilenames(prefs, filenameTable, filenameIdx, outFileName, suffix, dictFileName, cLevel, compressionParams);
+          operationResult = FIO_compressMultipleFilenames(prefs, filenameTable, outDirName, filenameIdx, outFileName, suffix, dictFileName, cLevel, compressionParams);
 #else
         (void)suffix; (void)adapt; (void)rsyncable; (void)ultra; (void)cLevel; (void)ldmFlag; (void)literalCompressionMode; (void)targetCBlockSize; (void)streamSrcSize; (void)srcSizeHint; /* not used when ZSTD_NOCOMPRESS set */
         DISPLAY("Compression not supported \n");
@@ -1184,7 +1195,7 @@ int main(int argCount, const char* argv[])
         if (filenameIdx==1 && outFileName)
             operationResult = FIO_decompressFilename(prefs, outFileName, filenameTable[0], dictFileName);
         else
-            operationResult = FIO_decompressMultipleFilenames(prefs, filenameTable, filenameIdx, outFileName, dictFileName);
+            operationResult = FIO_decompressMultipleFilenames(prefs, filenameTable, filenameIdx, outDirName, outFileName, dictFileName);
 #else
         DISPLAY("Decompression not supported \n");
 #endif
diff --git a/tests/playTests.sh b/tests/playTests.sh
index 5a47ceb5e..06de4f8ac 100755
--- a/tests/playTests.sh
+++ b/tests/playTests.sh
@@ -269,6 +269,24 @@ if [ "$?" -eq 139 ]; then
 fi
 rm tmp*
 
+println "test : compress multiple files into an output directory, --output-dir-flat"
+println henlo > tmp1
+mkdir tmpInputTestDir
+mkdir tmpInputTestDir/we
+mkdir tmpInputTestDir/we/must
+mkdir tmpInputTestDir/we/must/go
+mkdir tmpInputTestDir/we/must/go/deeper
+println cool > tmpInputTestDir/we/must/go/deeper/tmp2
+mkdir tmpOutDir
+$ZSTD tmp1 tmpInputTestDir/we/must/go/deeper/tmp2 --output-dir-flat tmpOutDir
+test -f tmpOutDir/tmp1.zst
+test -f tmpOutDir/tmp2.zst
+println "test : decompress multiple files into an output directory, --output-dir-flat"
+mkdir tmpOutDirDecomp
+$ZSTD tmpOutDir/ -r -d --output-dir-flat tmpOutDirDecomp
+test -f tmpOutDirDecomp/tmp2
+test -f tmpOutDirDecomp/tmp1
+rm -rf tmp*
 
 println "\n===>  Advanced compression parameters "
 println "Hello world!" | $ZSTD --zstd=windowLog=21,      - -o tmp.zst && die "wrong parameters not detected!"
@@ -412,7 +430,6 @@ ls -ls tmp* # check size of tmpdec (should be 2*(tmp1 + tmp2 + tmp3))
 println "compress multiple files including a missing one (notHere) : "
 $ZSTD -f tmp1 notHere tmp2 && die "missing file not detected!"
 
-
 println "\n===>  stream-size mode"
 
 ./datagen -g11000 > tmp