diff --git a/indra/llmessage/llhttpclient.cpp b/indra/llmessage/llhttpclient.cpp
index bd40d8e69..ac2438c4b 100644
--- a/indra/llmessage/llhttpclient.cpp
+++ b/indra/llmessage/llhttpclient.cpp
@@ -243,7 +243,9 @@ bool LLHTTPClient::getByteRange(std::string const& url, AIHTTPHeaders& headers,
 	{
 		if (offset > 0 || bytes > 0)
 		{
-			headers.addHeader("Range", llformat("bytes=%d-%d", offset, offset + bytes - 1));
+			int const range_end = offset + bytes - 1;
+			char const* const range_format = (range_end >= HTTP_REQUESTS_RANGE_END_MAX) ? "bytes=%d-" : "bytes=%d-%d";
+			headers.addHeader("Range", llformat(range_format, offset, range_end));
 		}
 		request(url, HTTP_GET, NULL, responder, headers, NULL/*,*/ DEBUG_CURLIO_PARAM(debug));
 	}
diff --git a/indra/llmessage/llhttpclient.h b/indra/llmessage/llhttpclient.h
index 3bb60b04f..dbbf729ac 100644
--- a/indra/llmessage/llhttpclient.h
+++ b/indra/llmessage/llhttpclient.h
@@ -55,6 +55,17 @@ typedef struct _xmlrpc_request* XMLRPC_REQUEST;
 typedef struct _xmlrpc_value* XMLRPC_VALUE;
 extern AIEngine gMainThreadEngine;
 
+// In Viewer 3 this definition is in indra/newview/lltexturefetch.cpp,
+// but we need it in two .cpp files, so it's moved here.
+//
+// BUG-3323/SH-4375
+// *NOTE:  This is a heuristic value.  Texture fetches have a habit of using a
+// value of 32MB to indicate 'get the rest of the image'.  Certain ISPs and
+// network equipment get confused when they see this in a Range: header.  So,
+// if the request end is beyond this value, we issue an open-ended Range:
+// request (e.g. 'Range: <start>-') which seems to fix the problem.
+static const S32 HTTP_REQUESTS_RANGE_END_MAX = 20000000;
+
 // Output parameter of AICurlPrivate::CurlEasyRequest::getResult.
 // Used in XMLRPCResponder.
 struct AITransferInfo {
diff --git a/indra/newview/lltexturefetch.cpp b/indra/newview/lltexturefetch.cpp
index 2079180fd..7df177ad0 100644
--- a/indra/newview/lltexturefetch.cpp
+++ b/indra/newview/lltexturefetch.cpp
@@ -1416,7 +1416,9 @@ bool LLTextureFetchWorker::doWork(S32 param)
 			// Call LLHTTPClient::request directly instead of LLHTTPClient::getByteRange, because we want to pass a NULL AIEngine.
 			if (mRequestedOffset > 0 || mRequestedSize > 0)
 			{
-				headers.addHeader("Range", llformat("bytes=%d-%d", mRequestedOffset, mRequestedOffset + mRequestedSize - 1));
+				int const range_end = mRequestedOffset + mRequestedSize - 1;
+				char const* const range_format = (range_end >= HTTP_REQUESTS_RANGE_END_MAX) ? "bytes=%d-" : "bytes=%d-%d";
+				headers.addHeader("Range", llformat(range_format, mRequestedOffset, range_end));
 			}
 			LLHTTPClient::request(mUrl, LLHTTPClient::HTTP_GET, NULL,
 				new HTTPGetResponder(mFetcher, mID, LLTimer::getTotalTime(), mRequestedSize, mRequestedOffset),