diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -3004,6 +3004,15 @@
   SmallVector<OMPTraitInfo *, 4> OMPTraitInfoVector;
 };
 
+/// Insertion operator for diagnostics.
+inline const DiagnosticBuilder &
+operator<<(const DiagnosticBuilder &DB,
+           const ASTContext::SectionInfo &Section) {
+  if (Section.Decl)
+    return DB << Section.Decl;
+  return DB << "a prior #pragma section";
+}
+
 /// Utility function for constructing a nullary selector.
 inline Selector GetNullarySelector(StringRef name, ASTContext &Ctx) {
   IdentifierInfo* II = &Ctx.Idents.get(name);
diff --git a/clang/lib/Sema/SemaAttr.cpp b/clang/lib/Sema/SemaAttr.cpp
--- a/clang/lib/Sema/SemaAttr.cpp
+++ b/clang/lib/Sema/SemaAttr.cpp
@@ -471,42 +471,49 @@
 bool Sema::UnifySection(StringRef SectionName,
                         int SectionFlags,
                         DeclaratorDecl *Decl) {
-  auto Section = Context.SectionInfos.find(SectionName);
-  if (Section == Context.SectionInfos.end()) {
+  SourceLocation PragmaLocation;
+  if (auto A = Decl->getAttr<SectionAttr>())
+    if (A->isImplicit())
+      PragmaLocation = A->getLocation();
+  auto SectionIt = Context.SectionInfos.find(SectionName);
+  if (SectionIt == Context.SectionInfos.end()) {
     Context.SectionInfos[SectionName] =
-        ASTContext::SectionInfo(Decl, SourceLocation(), SectionFlags);
+        ASTContext::SectionInfo(Decl, PragmaLocation, SectionFlags);
     return false;
   }
   // A pre-declared section takes precedence w/o diagnostic.
-  if (Section->second.SectionFlags == SectionFlags ||
-      !(Section->second.SectionFlags & ASTContext::PSF_Implicit))
+  const auto &Section = SectionIt->second;
+  if (Section.SectionFlags == SectionFlags ||
+      ((SectionFlags & ASTContext::PSF_Implicit) &&
+       !(Section.SectionFlags & ASTContext::PSF_Implicit)))
     return false;
-  auto OtherDecl = Section->second.Decl;
-  Diag(Decl->getLocation(), diag::err_section_conflict)
-      << Decl << OtherDecl;
-  Diag(OtherDecl->getLocation(), diag::note_declared_at)
-      << OtherDecl->getName();
-  if (auto A = Decl->getAttr<SectionAttr>())
-    if (A->isImplicit())
-      Diag(A->getLocation(), diag::note_pragma_entered_here);
-  if (auto A = OtherDecl->getAttr<SectionAttr>())
-    if (A->isImplicit())
-      Diag(A->getLocation(), diag::note_pragma_entered_here);
+  Diag(Decl->getLocation(), diag::err_section_conflict) << Decl << Section;
+  if (Section.Decl)
+    Diag(Section.Decl->getLocation(), diag::note_declared_at)
+        << Section.Decl->getName();
+  if (PragmaLocation.isValid())
+    Diag(PragmaLocation, diag::note_pragma_entered_here);
+  if (Section.PragmaSectionLocation.isValid())
+    Diag(Section.PragmaSectionLocation, diag::note_pragma_entered_here);
   return true;
 }
 
 bool Sema::UnifySection(StringRef SectionName,
                         int SectionFlags,
                         SourceLocation PragmaSectionLocation) {
-  auto Section = Context.SectionInfos.find(SectionName);
-  if (Section != Context.SectionInfos.end()) {
-    if (Section->second.SectionFlags == SectionFlags)
+  auto SectionIt = Context.SectionInfos.find(SectionName);
+  if (SectionIt != Context.SectionInfos.end()) {
+    const auto &Section = SectionIt->second;
+    if (Section.SectionFlags == SectionFlags)
       return false;
-    if (!(Section->second.SectionFlags & ASTContext::PSF_Implicit)) {
+    if (!(Section.SectionFlags & ASTContext::PSF_Implicit)) {
       Diag(PragmaSectionLocation, diag::err_section_conflict)
-          << "this" << "a prior #pragma section";
-      Diag(Section->second.PragmaSectionLocation,
-           diag::note_pragma_entered_here);
+          << "this" << Section;
+      if (Section.Decl)
+        Diag(Section.Decl->getLocation(), diag::note_declared_at)
+            << Section.Decl->getName();
+      if (Section.PragmaSectionLocation.isValid())
+        Diag(Section.PragmaSectionLocation, diag::note_pragma_entered_here);
       return true;
     }
   }
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -12746,7 +12746,7 @@
   if (GlobalStorage && var->isThisDeclarationADefinition() &&
       !inTemplateInstantiation()) {
     PragmaStack<StringLiteral *> *Stack = nullptr;
-    int SectionFlags = ASTContext::PSF_Implicit | ASTContext::PSF_Read;
+    int SectionFlags = ASTContext::PSF_Read;
     if (var->getType().isConstQualified())
       Stack = &ConstSegStack;
     else if (!var->getInit()) {
@@ -12756,14 +12756,19 @@
       Stack = &DataSegStack;
       SectionFlags |= ASTContext::PSF_Write;
     }
-    if (Stack->CurrentValue && !var->hasAttr<SectionAttr>())
+    if (const SectionAttr *SA = var->getAttr<SectionAttr>()) {
+      if (SA->getSyntax() == AttributeCommonInfo::AS_Declspec)
+        SectionFlags |= ASTContext::PSF_Implicit;
+      UnifySection(SA->getName(), SectionFlags, var);
+    } else if (Stack->CurrentValue) {
+      SectionFlags |= ASTContext::PSF_Implicit;
+      auto SectionName = Stack->CurrentValue->getString();
       var->addAttr(SectionAttr::CreateImplicit(
-          Context, Stack->CurrentValue->getString(),
-          Stack->CurrentPragmaLocation, AttributeCommonInfo::AS_Pragma,
-          SectionAttr::Declspec_allocate));
-    if (const SectionAttr *SA = var->getAttr<SectionAttr>())
-      if (UnifySection(SA->getName(), SectionFlags, var))
+          Context, SectionName, Stack->CurrentPragmaLocation,
+          AttributeCommonInfo::AS_Pragma, SectionAttr::Declspec_allocate));
+      if (UnifySection(SectionName, SectionFlags, var))
         var->dropAttr<SectionAttr>();
+    }
 
     // Apply the init_seg attribute if this has an initializer.  If the
     // initializer turns out to not be dynamic, we'll end up ignoring this
diff --git a/clang/test/Sema/pragma-clang-section.c b/clang/test/Sema/pragma-clang-section.c
--- a/clang/test/Sema/pragma-clang-section.c
+++ b/clang/test/Sema/pragma-clang-section.c
@@ -22,4 +22,9 @@
 #pragma clang section bss = "myrodata.1"               // expected-error {{this causes a section type conflict with a prior #pragma section}}
 #pragma clang section text = "mybss.3"                 // expected-error {{this causes a section type conflict with a prior #pragma section}}
 
+#pragma clang section rodata = "myrodata.4"              // expected-note {{#pragma entered here}}
+int x __attribute__((section("myrodata.4")));            // expected-error {{'x' causes a section type conflict with a prior #pragma section}}
+const int y __attribute__((section("myrodata.5"))) = 10; // expected-note {{declared here}}
+#pragma clang section data = "myrodata.5"                // expected-error {{this causes a section type conflict with 'y'}}
+
 int a;