diff --git a/MANUAL.txt b/MANUAL.txt
index bc9e226e9..845d1dbba 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -4240,6 +4240,22 @@ will be interpreted as markdown. For example:
       \renewcommand{\section}[1]{\clearpage\oldsection{#1}}
       ```
 
+Note:  the `yaml_metadata_block` extension works with
+`commonmark` as well as `markdown` (and it is enabled by default
+in `gfm` and `commonmark_x`).  However, in these formats the
+following restrictions apply:
+
+- The YAML metadata block must occur at the beginning of the
+  document (and there can be only one).  If multiple files are
+  given as arguments to pandoc, only the first can be a YAML
+  metadata block.
+
+- The leaf nodes of the YAML structure are parsed in isolation from
+  each other and from the rest of the document.  So, for
+  example,  you can't use a reference link in these contexts
+  if the link definition is somewhere else in the document.
+
+
 ## Backslash escapes
 
 #### Extension: `all_symbols_escapable` ####
diff --git a/src/Text/Pandoc/Extensions.hs b/src/Text/Pandoc/Extensions.hs
index 266a09e3c..6423d5f56 100644
--- a/src/Text/Pandoc/Extensions.hs
+++ b/src/Text/Pandoc/Extensions.hs
@@ -354,6 +354,7 @@ getDefaultExtensions "gfm"             = extensionsFromList
   , Ext_strikeout
   , Ext_task_lists
   , Ext_emoji
+  , Ext_yaml_metadata_block
   ]
 getDefaultExtensions "commonmark"      = extensionsFromList
                                           [Ext_raw_html]
@@ -379,6 +380,7 @@ getDefaultExtensions "commonmark_x"    = extensionsFromList
   , Ext_raw_attribute
   , Ext_implicit_header_references
   , Ext_attributes
+  , Ext_yaml_metadata_block
   ]
 getDefaultExtensions "org"             = extensionsFromList
                                           [Ext_citations,
@@ -511,6 +513,7 @@ getAllExtensions f = universalExtensions <> getAll f
     , Ext_implicit_header_references
     , Ext_attributes
     , Ext_sourcepos
+    , Ext_yaml_metadata_block
     ]
   getAll "commonmark_x"    = getAll "commonmark"
   getAll "org"             = autoIdExtensions <>
diff --git a/src/Text/Pandoc/Parsing.hs b/src/Text/Pandoc/Parsing.hs
index 44e6af59e..0c2078721 100644
--- a/src/Text/Pandoc/Parsing.hs
+++ b/src/Text/Pandoc/Parsing.hs
@@ -517,7 +517,7 @@ parseFromString :: (Stream s m Char, IsString s)
                 -> ParserT s st m r
 parseFromString parser str = do
   oldPos <- getPosition
-  setPosition $ initialPos "chunk"
+  setPosition $ initialPos " chunk"
   oldInput <- getInput
   setInput $ fromString $ T.unpack str
   result <- parser
diff --git a/src/Text/Pandoc/Readers/CommonMark.hs b/src/Text/Pandoc/Readers/CommonMark.hs
index 150a837e4..244f77940 100644
--- a/src/Text/Pandoc/Readers/CommonMark.hs
+++ b/src/Text/Pandoc/Readers/CommonMark.hs
@@ -26,13 +26,43 @@ import Text.Pandoc.Definition
 import Text.Pandoc.Builder as B
 import Text.Pandoc.Options
 import Text.Pandoc.Error
+import Text.Pandoc.Readers.Metadata (yamlMetaBlock)
 import Control.Monad.Except
 import Data.Functor.Identity (runIdentity)
 import Data.Typeable
+import Text.Pandoc.Parsing (runParserT, getPosition, sourceLine,
+                            runF, defaultParserState, take1WhileP, option)
+import qualified Data.Text as T
 
 -- | Parse a CommonMark formatted string into a 'Pandoc' structure.
 readCommonMark :: PandocMonad m => ReaderOptions -> Text -> m Pandoc
 readCommonMark opts s
+  | isEnabled Ext_yaml_metadata_block opts
+  , "---" `T.isPrefixOf` s = do
+       let metaValueParser = do
+             inp <- option "" $ take1WhileP (const True)
+             case runIdentity
+                    (commonmarkWith (specFor opts) "metadata value" inp) of
+                    Left _ -> mzero
+                    Right (Cm bls :: Cm () Blocks)
+                             -> return $ return $ B.toMetaValue bls
+       res <- runParserT (do meta <- yamlMetaBlock metaValueParser
+                             pos <- getPosition
+                             return (meta, pos))
+                         defaultParserState "YAML metadata" s
+       case res of
+         Left _ -> readCommonMarkBody opts s
+         Right (meta, pos) -> do
+           let dropLines 0 = id
+               dropLines n = dropLines (n - 1) . T.drop 1 . T.dropWhile (/='\n')
+           let metaLines = sourceLine pos - 1
+           let body = T.replicate metaLines "\n" <> dropLines metaLines s
+           Pandoc _ bs <- readCommonMarkBody opts body
+           return $ Pandoc (runF meta defaultParserState) bs
+  | otherwise = readCommonMarkBody opts s
+
+readCommonMarkBody :: PandocMonad m => ReaderOptions -> Text -> m Pandoc
+readCommonMarkBody opts s
   | isEnabled Ext_sourcepos opts =
     case runIdentity (commonmarkWith (specFor opts) "" s) of
       Left err -> throwError $ PandocParsecError s err