From: Hans Petter Jansson <hpj@copyleft.no>
      Wolfgang Rosenauer <wr@rosenauer.org>
Subject: use libnsssharedhelper if available at compile time
         (can be disabled by exporting MOZ_XRE_NO_NSSHELPER=1)
References:

diff --git a/configure.in b/configure.in
--- a/configure.in
+++ b/configure.in
@@ -8231,16 +8231,31 @@ if test "$MOZ_ENABLE_SKIA"; then
     MOZ_ENABLE_SKIA_GPU=1
     AC_DEFINE(USE_SKIA_GPU)
     AC_SUBST(MOZ_ENABLE_SKIA_GPU)
   fi
 fi
 AC_SUBST(MOZ_ENABLE_SKIA)
 
 dnl ========================================================
+dnl Check for nss-shared-helper
+dnl ========================================================
+
+  PKG_CHECK_MODULES(NSSHELPER, nss-shared-helper,
+    [MOZ_ENABLE_NSSHELPER=1],
+    [MOZ_ENABLE_NSSHELPER=])
+
+if test "$MOZ_ENABLE_NSSHELPER"; then
+  AC_DEFINE(MOZ_ENABLE_NSSHELPER)
+fi
+AC_SUBST(MOZ_ENABLE_NSSHELPER)
+AC_SUBST(NSSHELPER_CFLAGS)
+AC_SUBST(NSSHELPER_LIBS)
+
+dnl ========================================================
 dnl disable xul
 dnl ========================================================
 MOZ_ARG_DISABLE_BOOL(xul,
 [  --disable-xul           Disable XUL],
     MOZ_XUL= )
 if test "$MOZ_XUL"; then
   AC_DEFINE(MOZ_XUL)
 else
diff --git a/security/manager/ssl/src/Makefile.in b/security/manager/ssl/src/Makefile.in
new file mode 100644
--- /dev/null
+++ b/security/manager/ssl/src/Makefile.in
@@ -0,0 +1,8 @@
+#! gmake
+# 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+LOCAL_INCLUDES += $(NSSHELPER_CFLAGS)
+EXTRA_DSO_LDOPTS += $(NSSHELPER_LIBS)
diff --git a/security/manager/ssl/src/nsNSSComponent.cpp b/security/manager/ssl/src/nsNSSComponent.cpp
--- a/security/manager/ssl/src/nsNSSComponent.cpp
+++ b/security/manager/ssl/src/nsNSSComponent.cpp
@@ -3,16 +3,23 @@
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifdef MOZ_LOGGING
 #define FORCE_PR_LOG 1
 #endif
 
+#ifdef MOZ_ENABLE_NSSHELPER
+#pragma GCC visibility push(default)
+#include <nss-shared-helper.h>
+#pragma GCC visibility pop
+#include "prenv.h"
+#endif
+
 #include "nsNSSComponent.h"
 
 #include "ExtendedValidation.h"
 #include "NSSCertDBTrustDomain.h"
 #include "mozilla/Telemetry.h"
 #include "nsCertVerificationThread.h"
 #include "nsAppDirectoryServiceDefs.h"
 #include "nsComponentManagerUtils.h"
@@ -1141,17 +1148,31 @@ nsNSSComponent::InitializeNSS()
   if (NS_FAILED(rv)) {
     nsPSMInitPanic::SetPanic();
     return NS_ERROR_NOT_AVAILABLE;
   }
 
   SECStatus init_rv = SECFailure;
   if (!profileStr.IsEmpty()) {
     // First try to initialize the NSS DB in read/write mode.
-    SECStatus init_rv = ::mozilla::psm::InitializeNSS(profileStr.get(), false);
+#ifdef MOZ_ENABLE_NSSHELPER
+    if (PR_GetEnv("MOZ_TB_NO_NSSHELPER")) {
+      init_rv = ::mozilla::psm::InitializeNSS(profileStr.get(), false);
+    } else {
+      uint32_t flags = NSS_INIT_NOROOTINIT | NSS_INIT_OPTIMIZESPACE;
+      init_rv = ::nsshelp_open_db ("Thunderbird", profileStr.get(), flags);
+
+      if (init_rv != SECSuccess) {
+        PR_LOG(gPIPNSSLog, PR_LOG_DEBUG, ("can not init NSS using nsshelp_open_db in %s\n", profileStr.get()));
+        init_rv = ::mozilla::psm::InitializeNSS(profileStr.get(), false);
+      }
+    }
+#else
+    init_rv = ::mozilla::psm::InitializeNSS(profileStr.get(), false);
+#endif
     // If that fails, attempt read-only mode.
     if (init_rv != SECSuccess) {
       PR_LOG(gPIPNSSLog, PR_LOG_DEBUG, ("could not init NSS r/w in %s\n", profileStr.get()));
       init_rv = ::mozilla::psm::InitializeNSS(profileStr.get(), true);
     }
     if (init_rv != SECSuccess) {
       PR_LOG(gPIPNSSLog, PR_LOG_DEBUG, ("could not init in r/o either\n"));
     }
diff --git a/toolkit/library/libxul.mk b/toolkit/library/libxul.mk
--- a/toolkit/library/libxul.mk
+++ b/toolkit/library/libxul.mk
@@ -146,17 +146,17 @@ OS_LIBS += $(call EXPAND_LIBNAME,mfuuid 
 endif
 
 ifdef MOZ_DIRECTSHOW
 OS_LIBS += $(call EXPAND_LIBNAME,dmoguids wmcodecdspuuid strmiids msdmo)
 endif
 
 EXTRA_DSO_LDOPTS += $(LIBS_DIR)
 
-EXTRA_DSO_LDOPTS += $(NSPR_LIBS) $(MOZALLOC_LIB)
+EXTRA_DSO_LDOPTS += $(NSPR_LIBS) $(MOZALLOC_LIB) $(NSSHELPER_LIBS)
 
 ifeq ($(MOZ_WIDGET_TOOLKIT),cocoa)
 OS_LIBS += \
   $(TK_LIBS) \
   $(NULL)
 endif
 
 ifeq (OpenBSD,$(OS_ARCH))