diff --git a/configure/os/CONFIG.Common.solaris-sparc b/configure/os/CONFIG.Common.solaris-sparc
index d47a5165e..6f43ae4fa 100644
--- a/configure/os/CONFIG.Common.solaris-sparc
+++ b/configure/os/CONFIG.Common.solaris-sparc
@@ -21,7 +21,6 @@ COMPILER_LDFLAGS += -mt
 SOLARIS_VERSION = $(subst 5.,,$(shell uname -r))
 
 POSIX_CPPFLAGS += -D_POSIX_C_SOURCE=199506L $(POSIX_CPPFLAGS_$(SOLARIS_VERSION))
-POSIX_CPPFLAGS += -D_XOPEN_SOURCE=500
 POSIX_LDLIBS += -lposix4 -lpthread $(POSIX_LDLIBS_$(SOLARIS_VERSION))
 
 OP_SYS_CPPFLAGS += -DSOLARIS=$(SOLARIS_VERSION) $(COMPILER_CPPFLAGS)
diff --git a/configure/os/CONFIG.Common.solaris-x86 b/configure/os/CONFIG.Common.solaris-x86
index d19083422..6dc67fb5d 100644
--- a/configure/os/CONFIG.Common.solaris-x86
+++ b/configure/os/CONFIG.Common.solaris-x86
@@ -21,7 +21,6 @@ COMPILER_LDFLAGS += -mt
 SOLARIS_VERSION = $(subst 5.,,$(shell uname -r))
 
 POSIX_CPPFLAGS += -D_POSIX_C_SOURCE=199506L $(POSIX_CPPFLAGS_$(SOLARIS_VERSION))
-POSIX_CPPFLAGS += -D_XOPEN_SOURCE=500
 POSIX_LDLIBS += -lposix4 -lpthread $(POSIX_LDLIBS_$(SOLARIS_VERSION))
 
 OP_SYS_CPPFLAGS += -DSOLARIS=$(SOLARIS_VERSION) $(COMPILER_CPPFLAGS)
@@ -53,6 +52,7 @@ OP_SYS_LDLIBS += -lsocket -lnsl
 OP_SYS_LDLIBS_8 += -ldl -lCrun -lc
 OP_SYS_LDLIBS_9 += -ldl -lCrun -lc
 OP_SYS_LDLIBS_10 += -lCrun -lc
+OP_SYS_LDLIBS_11 += -lCrun -lc
 OP_SYS_LDLIBS += $(OP_SYS_LDLIBS_$(SOLARIS_VERSION))
 OP_SYS_LDLIBS += $(STLPORT_LDLIBS_$(USE_STLPORT))
 
diff --git a/configure/os/CONFIG.Common.solaris-x86-gnu b/configure/os/CONFIG.Common.solaris-x86-gnu
index ce4fae0ad..25a63edbe 100644
--- a/configure/os/CONFIG.Common.solaris-x86-gnu
+++ b/configure/os/CONFIG.Common.solaris-x86-gnu
@@ -17,4 +17,5 @@ STLPORT_LDLIBS_NO =
 OP_SYS_LDLIBS_8 = -ldl -lc
 OP_SYS_LDLIBS_9 = -ldl -lc
 OP_SYS_LDLIBS_10 = -lc
+OP_SYS_LDLIBS_11 = -lc
 
diff --git a/configure/os/CONFIG.solarisCommon.solarisCommon b/configure/os/CONFIG.solarisCommon.solarisCommon
index c38fc92d8..027124654 100644
--- a/configure/os/CONFIG.solarisCommon.solarisCommon
+++ b/configure/os/CONFIG.solarisCommon.solarisCommon
@@ -7,9 +7,10 @@
 # Sites may override these definitions in CONFIG_SITE.solaris-sparc.solaris-sparc
 #-------------------------------------------------------
 
-SPARCWORKS = /opt/SUNWspro
 GNU = NO
 
+# SPARCWORKS path is set in a CONFIG_SITE file
+
 CC = $(SPARCWORKS)/bin/cc
 CCC = $(SPARCWORKS)/bin/CC
 CPP = $(CC) -E -Qn
diff --git a/configure/os/CONFIG_SITE.Common.solaris-sparc b/configure/os/CONFIG_SITE.Common.solaris-sparc
index 95d9b42d2..851254203 100644
--- a/configure/os/CONFIG_SITE.Common.solaris-sparc
+++ b/configure/os/CONFIG_SITE.Common.solaris-sparc
@@ -5,11 +5,12 @@
 # Site Specific definitions for solaris-sparc target
 # Only the local epics system manager should modify this file
 
-# If readline is installed uncomment the following macro definition
-# to include command-line editing and history support
-#
+# location of the Solaris Studio (was SunPro) compilers
+SPARCWORKS = /opt/SUNWspro
+#SPARCWORKS = /opt/solarisstudio12.3
 
-# Readline library provides command-line editing and history in IOC shell
+# If readline is installed, uncomment the following macro definition
+# to use it for command-line editing and history support
 #COMMANDLINE_LIBRARY = READLINE
 
 # Use stLport library instead of default Cstd library
diff --git a/configure/os/CONFIG_SITE.Common.solaris-x86 b/configure/os/CONFIG_SITE.Common.solaris-x86
new file mode 100644
index 000000000..2a972d9cb
--- /dev/null
+++ b/configure/os/CONFIG_SITE.Common.solaris-x86
@@ -0,0 +1,11 @@
+# CONFIG_SITE.Common.solaris-x86
+#
+# $Revision-Id$
+#
+# Site Specific definitions for solaris-x86 targets
+# Only the local epics system manager should modify this file
+
+# location of the Solaris Studio (was SunPro) compilers
+SPARCWORKS = /opt/SUNWspro
+#SPARCWORKS = /opt/solarisstudio12.3
+
diff --git a/configure/os/CONFIG_SITE.Common.solaris-x86_64 b/configure/os/CONFIG_SITE.Common.solaris-x86_64
index 315b93597..ce173608d 100644
--- a/configure/os/CONFIG_SITE.Common.solaris-x86_64
+++ b/configure/os/CONFIG_SITE.Common.solaris-x86_64
@@ -5,7 +5,7 @@
 # Site Specific definitions for solaris-x86_64 target
 # Only the local epics system manager should modify this file
 
-# Include definitions common to all solaris-x86_64 target archs
+# Include definitions common to all solaris-x86 target archs
 -include $(CONFIG)/os/CONFIG_SITE.Common.solaris-x86
 
 COMMANDLINE_LIBRARY = EPICS
diff --git a/configure/os/CONFIG_SITE.solaris-sparc.Common b/configure/os/CONFIG_SITE.solaris-sparc.Common
index d78cdadda..a7398dbcf 100644
--- a/configure/os/CONFIG_SITE.solaris-sparc.Common
+++ b/configure/os/CONFIG_SITE.solaris-sparc.Common
@@ -4,7 +4,4 @@
 #
 # Site specific override definitions for solaris-sparc host builds
 # Only the local epics system manager should modify this file
- 
-#INSTALL_LOCATION = /home/phoebus/JBA/testBaseNew
 
-#CROSS_COMPILER_TARGET_ARCHS += vxWorks-ppc604 vxWorks-ppc603 vxWorks-68040
diff --git a/documentation/RELEASE_NOTES.html b/documentation/RELEASE_NOTES.html
index 021f0e432..f4912390e 100644
--- a/documentation/RELEASE_NOTES.html
+++ b/documentation/RELEASE_NOTES.html
@@ -13,6 +13,14 @@
 
 <!-- Insert new items immediately below here ... -->
 
+<h3>Support for Solaris 11</h3>
+
+<p>The build rules have been updated to support Solaris 11. Note that APS staff
+may not be able to maintain EPICS on Solaris for much longer, so the existing
+support code is likely to bit-rot and future versions of the OS may not be able
+to build or run EPICS applications unless someone else picks up the maintenance
+tasks.</p>
+
 <h3>Generating OS-specific include files</h3>
 
 <p>A fix has been applied to the build rules to permit OS-specific header files
diff --git a/src/libCom/osi/os/solaris/epicsMath.h b/src/libCom/osi/os/solaris/epicsMath.h
index 1cf60b5db..87d4986a7 100644
--- a/src/libCom/osi/os/solaris/epicsMath.h
+++ b/src/libCom/osi/os/solaris/epicsMath.h
@@ -17,6 +17,10 @@
 /* same as (!isnan(x) && !finite(x)) */
 #endif
 
+#ifndef isnan
+#  define isnan(x) ((x) != (x))
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif