diff --git a/indra/llcommon/llthread.cpp b/indra/llcommon/llthread.cpp
index 43fe7596e..dd0efb422 100644
--- a/indra/llcommon/llthread.cpp
+++ b/indra/llcommon/llthread.cpp
@@ -29,6 +29,11 @@
  * $/LicenseInfo$
  */
 
+#ifdef __GNUC__
+// Generate code for inlines from llthread.h (needed for is_main_thread()).
+#pragma implementation "llthread.h"
+#endif
+
 #include "linden_common.h"
 #include "llapr.h"
 
diff --git a/indra/llcommon/llthread.h b/indra/llcommon/llthread.h
index cea8c32c2..ef4303a02 100644
--- a/indra/llcommon/llthread.h
+++ b/indra/llcommon/llthread.h
@@ -33,6 +33,12 @@
 #ifndef LL_LLTHREAD_H
 #define LL_LLTHREAD_H
 
+#ifdef __GNUC__
+// Needed for is_main_thread() when compiling with optimization (relwithdebinfo).
+// It doesn't hurt to just always specify it though.
+#pragma interface
+#endif
+
 #include "llapp.h"
 #include "llapr.h"
 #include "llmemory.h"
@@ -308,7 +314,7 @@ private:
 	LLMutexBase* mMutex;
 };
 
-class AIRWLock
+class LL_COMMON_API AIRWLock
 {
 public:
 	AIRWLock(LLAPRPool& parent = LLThread::tldata().mRootPool) :