Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -2279,6 +2279,11 @@
       if (auto *SA = D->getAttr<PragmaClangTextSectionAttr>())
         if (!D->getAttr<SectionAttr>())
           F->addFnAttr("implicit-section-name", SA->getName());
+      // If we have -ffunction-sections, and an explicit section name,
+      // and the function is not COMDAT, explicitly retain it.
+      if (CodeGenOpts.FunctionSections && D->hasAttr<SectionAttr>() &&
+          !F->getComdat())
+        addUsedGlobal(F);
 
       llvm::AttrBuilder Attrs(F->getContext());
       if (GetCPUAndFeaturesAttributes(GD, Attrs)) {
Index: clang/test/CodeGen/section-retain.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGen/section-retain.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -triple x86_64-linux -emit-llvm -o - %s | \
+// RUN:     FileCheck %s --check-prefix=UNUSED
+// RUN: %clang_cc1 -triple x86_64-linux -emit-llvm -ffunction-sections -o - %s | \
+// RUN:     FileCheck %s --check-prefix=USED
+
+// template function = comdat always.
+template<typename T>
+__attribute__((section("foo"))) T ftemplate(T a) { return a + 1; }
+__attribute__((section("foo"))) int fglobal(int a) { return ftemplate(a) + 2; }
+
+// UNUSED-NOT: llvm.used
+// USED: @llvm.used = {{.*}} [ptr
+// USED-NOT: ftemplate
+// USED-SAME: fglobal
+// USED-NOT: ftemplate
+// USED-SAME: ]
+
+// USED-DAG: define {{.*}}ftemplate{{.*}} section "foo"
+// USED-DAG: define {{.*}}fglobal{{.*}} section "foo"