diff -r 05aaccf7d558 -r 5b1eec609909 make/autoconf/flags-cflags.m4
--- a/make/autoconf/flags-cflags.m4	Mon Apr 29 16:01:52 2019 -0400
+++ b/make/autoconf/flags-cflags.m4	Fri Mar 08 18:21:52 2019 -0800
@@ -536,6 +536,12 @@
     TOOLCHAIN_CFLAGS_JVM="$TOOLCHAIN_CFLAGS_JVM -mno-omit-leaf-frame-pointer -mstack-alignment=16"
 
     if test "x$OPENJDK_TARGET_OS" = xlinux; then
+      if test "x$DEBUG_LEVEL" = xrelease; then
+        # Clang does not inline as much as GCC does for functions with "inline" keyword by default.
+        # This causes noticeable slowdown in pause time for G1, and possibly in other areas.
+        # Increasing the inline hint threshold avoids the slowdown for Clang-built JVM.
+        TOOLCHAIN_CFLAGS_JVM="$TOOLCHAIN_CFLAGS_JVM -mllvm -inlinehint-threshold=100000"
+      fi
       TOOLCHAIN_CFLAGS_JDK="-pipe"
       TOOLCHAIN_CFLAGS_JDK_CONLY="-fno-strict-aliasing" # technically NOT for CXX
     fi