--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -10143,16 +10143,20 @@ exports.PREFERENCES = [
     "-moz-font-feature-settings",
     "layout.css.prefixes.font-features"
   ],
   [
     "-moz-font-language-override",
     "layout.css.prefixes.font-features"
   ],
   [
+    "-moz-column-span",
+    "layout.css.column-span.enabled"
+  ],
+  [
     "-webkit-animation",
     "layout.css.prefixes.webkit"
   ],
   [
     "-webkit-animation-delay",
     "layout.css.prefixes.webkit"
   ],
   [

--- a/layout/style/nsCSSPropAliasList.h
+++ b/layout/style/nsCSSPropAliasList.h
@@ -254,16 +254,21 @@ CSS_PROP_ALIAS(-moz-column-rule-style,
                column_rule_style,
                MozColumnRuleStyle,
                "")
 CSS_PROP_ALIAS(-moz-column-rule-width,
                _moz_column_rule_width,
                column_rule_width,
                MozColumnRuleWidth,
                "")
+CSS_PROP_ALIAS(-moz-column-span,
+               _moz_column_span,
+               column_span,
+               MozColumnSpan,
+               "layout.css.column-span.enabled")
 CSS_PROP_ALIAS(-moz-column-width,
                _moz_column_width,
                column_width,
                MozColumnWidth,
                "")
 CSS_PROP_ALIAS(-moz-columns,
                _moz_columns,
                columns,

--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -8156,16 +8156,23 @@ if (IsCSSPropertyPrefEnabled("layout.css
   gCSSProperties["column-span"] = {
     domProp: "columnSpan",
     inherited: false,
     type: CSS_TYPE_LONGHAND,
     initial_values: [ "none" ],
     other_values: [ "all" ],
     invalid_values: [ "-1", "0", "auto", "2px" ]
   };
+  gCSSProperties["-moz-column-span"] = {
+    domProp: "MozColumnSpan",
+    inherited: false,
+    type: CSS_TYPE_SHORTHAND_AND_LONGHAND,
+    alias_for: "column-span",
+    subproperties: [ "column-span" ]
+  };
 }
 
 if (false) {
   // TODO These properties are chrome-only, and are not exposed via CSSOM.
   // We may still want to find a way to test them. See bug 1206999.
   gCSSProperties["-moz-window-shadow"] = {
     //domProp: "MozWindowShadow",
     inherited: false,