diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index 725bb0bced9c57..baed5ca22fa758 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -3287,8 +3287,12 @@ class ConceptDecl : public TemplateDecl, public Mergeable<ConceptDecl> {
     return isa<TemplateTypeParmDecl>(getTemplateParameters()->getParam(0));
   }
 
-  ConceptDecl *getCanonicalDecl() override { return getFirstDecl(); }
-  const ConceptDecl *getCanonicalDecl() const { return getFirstDecl(); }
+  ConceptDecl *getCanonicalDecl() override {
+    return cast<ConceptDecl>(getPrimaryMergedDecl(this));
+  }
+  const ConceptDecl *getCanonicalDecl() const {
+    return const_cast<ConceptDecl *>(this)->getCanonicalDecl();
+  }
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 8f887ce7829fa2..c0bec60f737c88 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -8754,7 +8754,8 @@ void Sema::CheckConceptRedefinition(ConceptDecl *NewDecl,
     //        Other decls (e.g. namespaces) also have this shortcoming.
     return;
   }
-  Context.setPrimaryMergedDecl(NewDecl, OldConcept);
+  // We unwrap canonical decl late to check for module visibility.
+  Context.setPrimaryMergedDecl(NewDecl, OldConcept->getCanonicalDecl());
 }
 
 /// \brief Strips various properties off an implicit instantiation
diff --git a/clang/test/Modules/merge-concepts.cpp b/clang/test/Modules/merge-concepts.cpp
index 9242f27633795b..c774157dd85b4e 100644
--- a/clang/test/Modules/merge-concepts.cpp
+++ b/clang/test/Modules/merge-concepts.cpp
@@ -28,6 +28,10 @@ module "library" {
 		export *
 		header "concepts.h"
 	}
+	module "compare" {
+		export *
+		header "compare.h"
+	}
 	module "format" {
 		export *
 		header "format.h"
@@ -47,19 +51,34 @@ module "library" {
 #define SAME_AS_H
 
 template <class T, class U>
-concept same_as = __is_same(T, U);
+concept same_as_impl = __is_same(T, U);
 
+template <class T, class U>
+concept same_as = same_as_impl<T, U> && same_as_impl<U, T>;
 #endif // SAME_AS_H
 
+
+//--- compare.h
+#ifndef COMPARE_H
+#define COMPARE_H
+
+#include "same_as.h"
+#include "concepts.h"
+
+template <class T> void foo()
+  requires same_as<T, int>
+{}
+#endif // COMPARE_H
+
 //--- format.h
 #ifndef FORMAT_H
 #define FORMAT_H
 
-#include "concepts.h"
 #include "same_as.h"
+#include "concepts.h"
 
-template <class T> void foo()
+template <class T> void bar()
   requires same_as<T, int>
 {}
 
-#endif // FORMAT_H
\ No newline at end of file
+#endif // FORMAT_H