diff --git a/llvm/lib/WindowsManifest/WindowsManifestMerger.cpp b/llvm/lib/WindowsManifest/WindowsManifestMerger.cpp
--- a/llvm/lib/WindowsManifest/WindowsManifestMerger.cpp
+++ b/llvm/lib/WindowsManifest/WindowsManifestMerger.cpp
@@ -348,6 +348,8 @@
           NewDefinedDefaultHref = TO_XML_CHAR(strdup(FROM_XML_CHAR(Def->href)));
         }
       } else if (!xmlStringsEqual(OriginalNsDef->href, Def->href)) {
+        if (NewDefinedDefaultHref)
+          xmlFree(const_cast<unsigned char *>(NewDefinedDefaultHref));
         return make_error<WindowsManifestError>(
             Twine("conflicting namespace definitions for ") +
             FROM_XML_CHAR(Def->prefix));
@@ -382,6 +384,9 @@
         Expected<xmlNsPtr> EC =
             searchOrDefine(OriginalDefinedDefaultHref, DominantNode);
         if (!EC) {
+          xmlFree(const_cast<unsigned char *>(OriginalDefinedDefaultHref));
+          if (NewDefinedDefaultHref)
+            xmlFree(const_cast<unsigned char *>(NewDefinedDefaultHref));
           return EC.takeError();
         }
         xmlNsPtr PrefixDominantDefinedDefault = std::move(EC.get());
@@ -400,6 +405,8 @@
         Expected<xmlNsPtr> EC =
             searchOrDefine(ClosestDefault->href, DominantNode);
         if (!EC) {
+          if (NewDefinedDefaultHref)
+            xmlFree(const_cast<unsigned char *>(NewDefinedDefaultHref));
           return EC.takeError();
         }
         xmlNsPtr ExplicitDefault = std::move(EC.get());
@@ -420,6 +427,10 @@
       Expected<xmlNsPtr> EC =
           searchOrDefine(DominantNode->ns->href, NonDominantNode);
       if (!EC) {
+        if (OriginalDefinedDefaultHref)
+          xmlFree(const_cast<unsigned char *>(OriginalDefinedDefaultHref));
+        if (NewDefinedDefaultHref)
+          xmlFree(const_cast<unsigned char *>(NewDefinedDefaultHref));
         return EC.takeError();
       }
       xmlNsPtr Explicit = std::move(EC.get());