diff --git a/lld/COFF/DebugTypes.cpp b/lld/COFF/DebugTypes.cpp
--- a/lld/COFF/DebugTypes.cpp
+++ b/lld/COFF/DebugTypes.cpp
@@ -125,18 +125,21 @@
 class PrecompSource : public TpiSource {
 public:
   PrecompSource(COFFLinkerContext &ctx, ObjFile *f) : TpiSource(ctx, PCH, f) {
-    if (!f->pchSignature || !*f->pchSignature)
-      fatal(toString(f) +
-            " claims to be a PCH object, but does not have a valid signature");
-    auto it = ctx.precompSourceMappings.emplace(*f->pchSignature, this);
-    if (!it.second)
-      fatal("a PCH object with the same signature has already been provided (" +
-            toString(it.first->second->file) + " and " + toString(file) + ")");
+    // If the S_OBJNAME record contains the PCH signature, we'll register this
+    // source file right away.
+    registerMapping();
   }
 
+  Error mergeDebugT(TypeMerger *m) override;
+
   void loadGHashes() override;
 
   bool isDependency() const override { return true; }
+
+private:
+  void registerMapping();
+
+  bool registered = false;
 };
 
 // This class represents the debug type stream of an OBJ file that depends on a
@@ -541,6 +544,30 @@
   return TpiSource::mergeDebugT(m);
 }
 
+Error PrecompSource::mergeDebugT(TypeMerger *m) {
+  if (Error e = TpiSource::mergeDebugT(m))
+    return e;
+
+  // In some cases, the S_OBJNAME record doesn't contain the PCH signature.
+  // The signature comes later with the LF_ENDPRECOMP record, so we first need
+  // to merge in all the .PCH.OBJ file type records.
+  registerMapping();
+
+  return Error::success();
+}
+
+void PrecompSource::registerMapping() {
+  if (registered)
+    return;
+  if (file->pchSignature && *file->pchSignature) {
+    auto it = ctx.precompSourceMappings.emplace(*file->pchSignature, this);
+    if (!it.second)
+      fatal("a PCH object with the same signature has already been provided (" +
+            toString(it.first->second->file) + " and " + toString(file) + ")");
+    registered = true;
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // Parellel GHash type merging implementation.
 //===----------------------------------------------------------------------===//
@@ -808,8 +835,15 @@
     // Remember the index of the LF_ENDPRECOMP record so it can be excluded from
     // the PDB. There must be an entry in the list of ghashes so that the type
     // indexes of the following records in the /Yc PCH object line up.
-    if (ty.kind() == LF_ENDPRECOMP)
+    if (ty.kind() == LF_ENDPRECOMP) {
+      if (!registered) {
+        EndPrecompRecord endPrecomp = cantFail(
+            TypeDeserializer::deserializeAs<EndPrecompRecord>(ty.data()));
+        file->pchSignature.emplace(endPrecomp.getSignature());
+        registerMapping();
+      }
       endPrecompGHashIdx = ghashIdx;
+    }
 
     hashVec.push_back(GloballyHashedType::hashType(ty, hashVec, hashVec));
     isItemIndex.push_back(isIdRecord(ty.kind()));
diff --git a/lld/test/COFF/precomp-link.test b/lld/test/COFF/precomp-link.test
--- a/lld/test/COFF/precomp-link.test
+++ b/lld/test/COFF/precomp-link.test
@@ -29,15 +29,13 @@
 
 RUN: obj2yaml %S/Inputs/precomp.obj | grep -v 'SectionData: *04000000' > %t.precomp.yaml
 RUN: sed '/S_OBJNAME/,/ObjectName:/d' < %t.precomp.yaml > precomp-no-objname.yaml
-RUN: sed 's/Signature: *545589255/Signature: 0/' < %t.precomp.yaml > precomp-zero-sig.yaml
+RUN: sed '16,19s/Signature: *545589255/Signature: 0/' < %t.precomp.yaml > precomp-zero-sig.yaml
 RUN: yaml2obj precomp-no-objname.yaml -o %t.precomp-no-objname.obj
 RUN: yaml2obj precomp-zero-sig.yaml -o %t.precomp-zero-sig.obj
 
-RUN: env LLD_IN_TEST=1 not lld-link %t.precomp-no-objname.obj %S/Inputs/precomp-a.obj %S/Inputs/precomp-b.obj /nodefaultlib /entry:main /debug /pdb:%t.pdb /out:%t.exe 2>&1 | FileCheck %s -check-prefix FAILURE-NO-SIGNATURE
+RUN: env LLD_IN_TEST=1 lld-link %t.precomp-no-objname.obj %S/Inputs/precomp-a.obj %S/Inputs/precomp-b.obj /nodefaultlib /entry:main /debug /pdb:%t.pdb /out:%t.exe 2>&1
 
-RUN: env LLD_IN_TEST=1 not lld-link %t.precomp-zero-sig.obj %S/Inputs/precomp-a.obj %S/Inputs/precomp-b.obj /nodefaultlib /entry:main /debug /pdb:%t.pdb /out:%t.exe 2>&1 | FileCheck %s -check-prefix FAILURE-NO-SIGNATURE
-
-FAILURE-NO-SIGNATURE: error: {{.*}}.obj claims to be a PCH object, but does not have a valid signature
+RUN: env LLD_IN_TEST=1 lld-link %t.precomp-zero-sig.obj %S/Inputs/precomp-a.obj %S/Inputs/precomp-b.obj /nodefaultlib /entry:main /debug /pdb:%t.pdb /out:%t.exe 2>&1
 
 Check that two PCH objs with duplicate signatures are an error.