diff --git a/indra/llcorehttp/_httpoprequest.cpp b/indra/llcorehttp/_httpoprequest.cpp
index 6186e7a308b..081a4d9bac9 100644
--- a/indra/llcorehttp/_httpoprequest.cpp
+++ b/indra/llcorehttp/_httpoprequest.cpp
@@ -538,6 +538,7 @@ HttpStatus HttpOpRequest::prepareRequest(HttpService * service)
     long sslHostV(0L);
     long dnsCacheTimeout(-1L);
     long nobody(0L);
+    curl_off_t lastModified(0L);
 
     if (mReqOptions)
     {
@@ -546,6 +547,7 @@ HttpStatus HttpOpRequest::prepareRequest(HttpService * service)
         sslHostV = mReqOptions->getSSLVerifyHost() ? 2L : 0L;
         dnsCacheTimeout = mReqOptions->getDNSCacheTimeout();
         nobody = mReqOptions->getHeadersOnly() ? 1L : 0L;
+        lastModified = (curl_off_t)mReqOptions->getLastModified();
     }
     check_curl_easy_setopt(mCurlHandle, CURLOPT_FOLLOWLOCATION, follow_redirect);
 
@@ -554,6 +556,17 @@ HttpStatus HttpOpRequest::prepareRequest(HttpService * service)
 
     check_curl_easy_setopt(mCurlHandle, CURLOPT_NOBODY, nobody);
 
+    if (lastModified)
+    {
+        check_curl_easy_setopt(mCurlHandle, CURLOPT_TIMECONDITION, CURL_TIMECOND_IFMODSINCE);
+#if (LIBCURL_VERSION_NUM >= 0x073B00)
+        // requires curl 7.59.0
+        check_curl_easy_setopt(mCurlHandle, CURLOPT_TIMEVALUE_LARGE, lastModified);
+#else
+        check_curl_easy_setopt(mCurlHandle, CURLOPT_TIMEVALUE, (long)lastModified);
+#endif
+    }
+
     // The Linksys WRT54G V5 router has an issue with frequent
     // DNS lookups from LAN machines.  If they happen too often,
     // like for every HTTP request, the router gets annoyed after
diff --git a/indra/llcorehttp/httpoptions.cpp b/indra/llcorehttp/httpoptions.cpp
index d85f6039b1c..5abd28e2112 100644
--- a/indra/llcorehttp/httpoptions.cpp
+++ b/indra/llcorehttp/httpoptions.cpp
@@ -47,6 +47,7 @@ HttpOptions::HttpOptions() :
     mVerifyPeer(sDefaultVerifyPeer),
     mVerifyHost(false),
     mDNSCacheTimeout(-1L),
+    mLastModified(0),
     mNoBody(false)
 {}
 
@@ -129,6 +130,11 @@ void HttpOptions::setHeadersOnly(bool nobody)
     }
 }
 
+void HttpOptions::setLastModified(time_t lastModified)
+{
+    mLastModified = lastModified;
+}
+
 void HttpOptions::setDefaultSSLVerifyPeer(bool verify)
 {
     sDefaultVerifyPeer = verify;
diff --git a/indra/llcorehttp/httpoptions.h b/indra/llcorehttp/httpoptions.h
index 56a28013cb4..fdb277c66ef 100644
--- a/indra/llcorehttp/httpoptions.h
+++ b/indra/llcorehttp/httpoptions.h
@@ -178,6 +178,13 @@ class HttpOptions : private boost::noncopyable
         return mNoBody;
     }
 
+    // Default:   0
+    void setLastModified(time_t lastModified);
+    time_t getLastModified() const
+    {
+        return mLastModified;
+    }
+
     /// Sets default behavior for verifying that the name in the
     /// security certificate matches the name of the host contacted.
     /// Defaults false if not set, but should be set according to
@@ -199,6 +206,7 @@ class HttpOptions : private boost::noncopyable
     bool                mVerifyHost;
     int                 mDNSCacheTimeout;
     bool                mNoBody;
+    time_t              mLastModified;
 
     static bool         sDefaultVerifyPeer;
 }; // end class HttpOptions
diff --git a/indra/newview/llviewernetwork.cpp b/indra/newview/llviewernetwork.cpp
index 16ddc2f89c1..f11fa09ce94 100644
--- a/indra/newview/llviewernetwork.cpp
+++ b/indra/newview/llviewernetwork.cpp
@@ -450,7 +450,7 @@ std::string LLGridManager::getGridLabel(const std::string& grid)
 {
     std::string grid_label;
     std::string grid_name = getGrid(grid);
-    if (!grid.empty())
+    if (!grid_name.empty())
     {
         grid_label = mGridList[grid_name][GRID_LABEL_VALUE].asString();
     }
@@ -466,7 +466,7 @@ std::string LLGridManager::getGridId(const std::string& grid)
 {
     std::string grid_id;
     std::string grid_name = getGrid(grid);
-    if (!grid.empty())
+    if (!grid_name.empty())
     {
         grid_id = mGridList[grid_name][GRID_ID_VALUE].asString();
     }