diff --git a/lib/ExecutionEngine/Orc/Core.cpp b/lib/ExecutionEngine/Orc/Core.cpp
index 8f920edb4fd..591aefb910e 100644
--- a/lib/ExecutionEngine/Orc/Core.cpp
+++ b/lib/ExecutionEngine/Orc/Core.cpp
@@ -488,8 +488,6 @@ void VSO::resolve(const SymbolMap &Resolved) {
     for (const auto &KV : Resolved) {
       auto &Name = KV.first;
       auto Sym = KV.second;
-      JITSymbolFlags ResolvedFlags = Sym.getFlags();
-      ResolvedFlags &= ~JITSymbolFlags::Weak;
 
       assert(!Sym.getFlags().isLazy() && !Sym.getFlags().isMaterializing() &&
              "Materializing flags should be managed internally");
@@ -502,11 +500,14 @@ void VSO::resolve(const SymbolMap &Resolved) {
              "Symbol should be materializing");
       assert(I->second.getAddress() == 0 && "Symbol has already been resolved");
 
-      assert(ResolvedFlags ==
-                 JITSymbolFlags::stripTransientFlags(I->second.getFlags()) &&
+      assert((Sym.getFlags() & ~JITSymbolFlags::Weak) ==
+                 (JITSymbolFlags::stripTransientFlags(I->second.getFlags()) &
+                  ~JITSymbolFlags::Weak) &&
              "Resolved flags should match the declared flags");
 
       // Once resolved, symbols can never be weak.
+      JITSymbolFlags ResolvedFlags = Sym.getFlags();
+      ResolvedFlags &= ~JITSymbolFlags::Weak;
       ResolvedFlags |= JITSymbolFlags::Materializing;
       I->second = JITEvaluatedSymbol(Sym.getAddress(), ResolvedFlags);
 
@@ -780,7 +781,6 @@ VSO::lookupImpl(std::shared_ptr<AsynchronousSymbolQuery> &Q,
       for (auto &KV : MU->getSymbols()) {
         auto SymK = Symbols.find(KV.first);
         auto Flags = SymK->second.getFlags();
-        Flags &= ~JITSymbolFlags::Weak;
         Flags &= ~JITSymbolFlags::Lazy;
         Flags |= JITSymbolFlags::Materializing;
         SymK->second.setFlags(Flags);
@@ -871,7 +871,8 @@ Error VSO::defineImpl(MaterializationUnit &MU) {
 
     if (!Added) {
       if (KV.second.isStrong()) {
-        if (EntryItr->second.getFlags().isStrong())
+        if (EntryItr->second.getFlags().isStrong() ||
+            (EntryItr->second.getFlags() & JITSymbolFlags::Materializing))
           Duplicates.insert(KV.first);
         else
           ExistingDefsOverridden.push_back(EntryItr);
@@ -905,8 +906,6 @@ Error VSO::defineImpl(MaterializationUnit &MU) {
            !ExistingDefItr->second.getFlags().isMaterializing() &&
            "Overridden existing def should be in the Lazy state");
 
-    ExistingDefItr->second.getFlags() &= ~JITSymbolFlags::Weak;
-
     auto UMII = UnmaterializedInfos.find(ExistingDefItr->first);
     assert(UMII != UnmaterializedInfos.end() &&
            "Overridden existing def should have an UnmaterializedInfo");